{"id":432,"date":"2026-10-07T08:47:51","date_gmt":"2026-10-07T08:47:51","guid":{"rendered":"https:\/\/helpwithmygisassignment.com\/blog\/?p=432"},"modified":"2026-10-07T08:48:25","modified_gmt":"2026-10-07T08:48:25","slug":"georeference-image-in-qgis","status":"publish","type":"post","link":"https:\/\/helpwithmygisassignment.com\/blog\/georeference-image-in-qgis\/","title":{"rendered":"ow to Georeference an Image in QGIS: 7 Easy Steps"},"content":{"rendered":"<div id=\"ez-toc-container\" class=\"ez-toc-v2_0_89 counter-hierarchy ez-toc-counter ez-toc-grey ez-toc-container-direction\">\n<div class=\"ez-toc-title-container\">\n<p class=\"ez-toc-title\" style=\"cursor:inherit\">Table of Contents<\/p>\n<span class=\"ez-toc-title-toggle\"><a href=\"#\" class=\"ez-toc-pull-right ez-toc-btn ez-toc-btn-xs ez-toc-btn-default ez-toc-toggle\" aria-label=\"Toggle Table of Content\"><span class=\"ez-toc-js-icon-con\"><span class=\"\"><span class=\"eztoc-hide\" style=\"display:none;\">Toggle<\/span><span class=\"ez-toc-icon-toggle-span\"><svg style=\"fill: #999;color:#999\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" class=\"list-377408\" width=\"20px\" height=\"20px\" viewBox=\"0 0 24 24\" fill=\"none\"><path d=\"M6 6H4v2h2V6zm14 0H8v2h12V6zM4 11h2v2H4v-2zm16 0H8v2h12v-2zM4 16h2v2H4v-2zm16 0H8v2h12v-2z\" fill=\"currentColor\"><\/path><\/svg><svg style=\"fill: #999;color:#999\" class=\"arrow-unsorted-368013\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" width=\"10px\" height=\"10px\" viewBox=\"0 0 24 24\" version=\"1.2\" baseProfile=\"tiny\"><path d=\"M18.2 9.3l-6.2-6.3-6.2 6.3c-.2.2-.3.4-.3.7s.1.5.3.7c.2.2.4.3.7.3h11c.3 0 .5-.1.7-.3.2-.2.3-.5.3-.7s-.1-.5-.3-.7zM5.8 14.7l6.2 6.3 6.2-6.3c.2-.2.3-.5.3-.7s-.1-.5-.3-.7c-.2-.2-.4-.3-.7-.3h-11c-.3 0-.5.1-.7.3-.2.2-.3.5-.3.7s.1.5.3.7z\"\/><\/svg><\/span><\/span><\/span><\/a><\/span><\/div>\n<nav><ul class='ez-toc-list ez-toc-list-level-1 ' ><li class='ez-toc-page-1 ez-toc-heading-level-1'><a class=\"ez-toc-link ez-toc-heading-1\" href=\"https:\/\/helpwithmygisassignment.com\/blog\/georeference-image-in-qgis\/#How_to_Georeference_an_Image_in_QGIS_A_Complete_Step-by-Step_Workflow\" >How to Georeference an Image in QGIS: A Complete Step-by-Step Workflow<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-1'><a class=\"ez-toc-link ez-toc-heading-2\" href=\"https:\/\/helpwithmygisassignment.com\/blog\/georeference-image-in-qgis\/#What_You_Need_Before_Starting\" >What You Need Before Starting<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-1'><a class=\"ez-toc-link ez-toc-heading-3\" href=\"https:\/\/helpwithmygisassignment.com\/blog\/georeference-image-in-qgis\/#Step_1_Load_the_Basemap_and_Set_the_Project_CRS\" >Step 1: Load the Basemap and Set the Project CRS<\/a><ul class='ez-toc-list-level-2' ><li class='ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-4\" href=\"https:\/\/helpwithmygisassignment.com\/blog\/georeference-image-in-qgis\/#11_Open_QGIS\" >1.1 Open QGIS<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-5\" href=\"https:\/\/helpwithmygisassignment.com\/blog\/georeference-image-in-qgis\/#12_Add_a_reference_layer\" >1.2 Add a reference layer<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-6\" href=\"https:\/\/helpwithmygisassignment.com\/blog\/georeference-image-in-qgis\/#13_Set_the_project_CRS\" >1.3 Set the project CRS<\/a><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-7\" href=\"https:\/\/helpwithmygisassignment.com\/blog\/georeference-image-in-qgis\/#Important_distinction\" >Important distinction<\/a><\/li><\/ul><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-1'><a class=\"ez-toc-link ez-toc-heading-8\" href=\"https:\/\/helpwithmygisassignment.com\/blog\/georeference-image-in-qgis\/#Step_2_Launch_the_Georeferencer_and_Select_Ground_Control_Points\" >Step 2: Launch the Georeferencer and Select Ground Control Points<\/a><ul class='ez-toc-list-level-2' ><li class='ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-9\" href=\"https:\/\/helpwithmygisassignment.com\/blog\/georeference-image-in-qgis\/#21_Load_the_scanned_map\" >2.1 Load the scanned map<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-1'><a class=\"ez-toc-link ez-toc-heading-10\" href=\"https:\/\/helpwithmygisassignment.com\/blog\/georeference-image-in-qgis\/#What_Are_Ground_Control_Points\" >What Are Ground Control Points?<\/a><ul class='ez-toc-list-level-2' ><li class='ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-11\" href=\"https:\/\/helpwithmygisassignment.com\/blog\/georeference-image-in-qgis\/#22_Choosing_good_GCPs\" >2.2 Choosing good GCPs<\/a><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-12\" href=\"https:\/\/helpwithmygisassignment.com\/blog\/georeference-image-in-qgis\/#Poor_distribution\" >Poor distribution<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-13\" href=\"https:\/\/helpwithmygisassignment.com\/blog\/georeference-image-in-qgis\/#Better_distribution\" >Better distribution<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-14\" href=\"https:\/\/helpwithmygisassignment.com\/blog\/georeference-image-in-qgis\/#23_Add_your_first_GCP\" >2.3 Add your first GCP<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-15\" href=\"https:\/\/helpwithmygisassignment.com\/blog\/georeference-image-in-qgis\/#24_Add_additional_GCPs\" >2.4 Add additional GCPs<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-1'><a class=\"ez-toc-link ez-toc-heading-16\" href=\"https:\/\/helpwithmygisassignment.com\/blog\/georeference-image-in-qgis\/#Step_3_Choose_Transformation_Settings_and_Understand_RMS_Error\" >Step 3: Choose Transformation Settings and Understand RMS Error<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-1'><a class=\"ez-toc-link ez-toc-heading-17\" href=\"https:\/\/helpwithmygisassignment.com\/blog\/georeference-image-in-qgis\/#Polynomial_1_vs_Thin_Plate_Spline\" >Polynomial 1 vs Thin Plate Spline<\/a><ul class='ez-toc-list-level-2' ><li class='ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-18\" href=\"https:\/\/helpwithmygisassignment.com\/blog\/georeference-image-in-qgis\/#Polynomial_1\" >Polynomial 1<\/a><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-19\" href=\"https:\/\/helpwithmygisassignment.com\/blog\/georeference-image-in-qgis\/#Use_Polynomial_1_when\" >Use Polynomial 1 when:<\/a><\/li><\/ul><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-1'><a class=\"ez-toc-link ez-toc-heading-20\" href=\"https:\/\/helpwithmygisassignment.com\/blog\/georeference-image-in-qgis\/#Thin_Plate_Spline\" >Thin Plate Spline<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-1'><a class=\"ez-toc-link ez-toc-heading-21\" href=\"https:\/\/helpwithmygisassignment.com\/blog\/georeference-image-in-qgis\/#Understanding_RMS_Error\" >Understanding RMS Error<\/a><ul class='ez-toc-list-level-2' ><li class='ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-22\" href=\"https:\/\/helpwithmygisassignment.com\/blog\/georeference-image-in-qgis\/#Dont_blindly_minimize_RMS_error\" >Don&#8217;t blindly minimize RMS error<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-1'><a class=\"ez-toc-link ez-toc-heading-23\" href=\"https:\/\/helpwithmygisassignment.com\/blog\/georeference-image-in-qgis\/#Step_4_Generate_and_Verify_the_GeoTIFF\" >Step 4: Generate and Verify the GeoTIFF<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-1'><a class=\"ez-toc-link ez-toc-heading-24\" href=\"https:\/\/helpwithmygisassignment.com\/blog\/georeference-image-in-qgis\/#41_Load_the_output_into_QGIS\" >4.1 Load the output into QGIS<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-1'><a class=\"ez-toc-link ez-toc-heading-25\" href=\"https:\/\/helpwithmygisassignment.com\/blog\/georeference-image-in-qgis\/#42_Verify_alignment_visually\" >4.2 Verify alignment visually<\/a><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-26\" href=\"https:\/\/helpwithmygisassignment.com\/blog\/georeference-image-in-qgis\/#Center\" >Center<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-27\" href=\"https:\/\/helpwithmygisassignment.com\/blog\/georeference-image-in-qgis\/#Edges\" >Edges<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-28\" href=\"https:\/\/helpwithmygisassignment.com\/blog\/georeference-image-in-qgis\/#Corners\" >Corners<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-29\" href=\"https:\/\/helpwithmygisassignment.com\/blog\/georeference-image-in-qgis\/#Independent_features\" >Independent features<\/a><\/li><\/ul><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-1'><a class=\"ez-toc-link ez-toc-heading-30\" href=\"https:\/\/helpwithmygisassignment.com\/blog\/georeference-image-in-qgis\/#Troubleshooting_Common_Georeferencing_Problems\" >Troubleshooting Common Georeferencing Problems<\/a><ul class='ez-toc-list-level-2' ><li class='ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-31\" href=\"https:\/\/helpwithmygisassignment.com\/blog\/georeference-image-in-qgis\/#Problem_1_RMS_Error_Is_Too_High\" >Problem 1: RMS Error Is Too High<\/a><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-32\" href=\"https:\/\/helpwithmygisassignment.com\/blog\/georeference-image-in-qgis\/#Check_your_GCPs\" >Check your GCPs<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-33\" href=\"https:\/\/helpwithmygisassignment.com\/blog\/georeference-image-in-qgis\/#Problem_2_The_Map_Is_Correct_in_the_Center_but_Wrong_at_the_Edges\" >Problem 2: The Map Is Correct in the Center but Wrong at the Edges<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-1'><a class=\"ez-toc-link ez-toc-heading-34\" href=\"https:\/\/helpwithmygisassignment.com\/blog\/georeference-image-in-qgis\/#Problem_3_The_Entire_Map_Is_Shifted\" >Problem 3: The Entire Map Is Shifted<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-1'><a class=\"ez-toc-link ez-toc-heading-35\" href=\"https:\/\/helpwithmygisassignment.com\/blog\/georeference-image-in-qgis\/#Problem_4_The_Raster_Is_Severely_Warped\" >Problem 4: The Raster Is Severely Warped<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-1'><a class=\"ez-toc-link ez-toc-heading-36\" href=\"https:\/\/helpwithmygisassignment.com\/blog\/georeference-image-in-qgis\/#Problem_5_Control_Points_Are_in_the_Wrong_Places\" >Problem 5: Control Points Are in the Wrong Places<\/a><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-37\" href=\"https:\/\/helpwithmygisassignment.com\/blog\/georeference-image-in-qgis\/#Solution\" >Solution<\/a><\/li><\/ul><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-1'><a class=\"ez-toc-link ez-toc-heading-38\" href=\"https:\/\/helpwithmygisassignment.com\/blog\/georeference-image-in-qgis\/#Problem_6_Historical_Features_Have_Changed\" >Problem 6: Historical Features Have Changed<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-1'><a class=\"ez-toc-link ez-toc-heading-39\" href=\"https:\/\/helpwithmygisassignment.com\/blog\/georeference-image-in-qgis\/#Recommended_GCP_Strategy\" >Recommended GCP Strategy<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-1'><a class=\"ez-toc-link ez-toc-heading-40\" href=\"https:\/\/helpwithmygisassignment.com\/blog\/georeference-image-in-qgis\/#Georeferencing_Checklist\" >Georeferencing Checklist<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-1'><a class=\"ez-toc-link ez-toc-heading-41\" href=\"https:\/\/helpwithmygisassignment.com\/blog\/georeference-image-in-qgis\/#Quick_Reference_Historical_Map_Georeferencing_in_QGIS\" >Quick Reference: Historical Map Georeferencing in QGIS<\/a><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-42\" href=\"https:\/\/helpwithmygisassignment.com\/blog\/georeference-image-in-qgis\/#%EF%B8%8F_Image_%E2%86%92_GCPs_%E2%86%92_Transformation_%E2%86%92_GeoTIFF_%E2%86%92_Validation\" >\ufe0f Image \u2192 GCPs \u2192 Transformation \u2192 GeoTIFF \u2192 Validation<\/a><\/li><\/ul><\/li><\/ul><\/li><\/ul><\/nav><\/div>\n<h1><span class=\"ez-toc-section\" id=\"How_to_Georeference_an_Image_in_QGIS_A_Complete_Step-by-Step_Workflow\"><\/span>How to Georeference an Image in QGIS: A Complete Step-by-Step Workflow<span class=\"ez-toc-section-end\"><\/span><\/h1>\n<p>Georeferencing assigns real-world geographic coordinates to an image that does not already contain spatial reference information. In this guide, you will learn <strong>how to georeference an image in QGIS<\/strong> using a scanned historical map, CAD print, aerial photograph, or other unreferenced raster. The process uses identifiable <strong>ground control points (GCPs)<\/strong>, a coordinate reference system (CRS), and a spatial transformation to align the image with modern geographic data.<\/p>\n<p>Georeferencing is particularly useful when working with historical maps because the original map may show roads, rivers, boundaries, or settlements without storing their modern geographic coordinates.<\/p>\n<hr \/>\n<h1><span class=\"ez-toc-section\" id=\"What_You_Need_Before_Starting\"><\/span>What You Need Before Starting<span class=\"ez-toc-section-end\"><\/span><\/h1>\n<p>Before diving into <b data-path-to-node=\"5,0,1,0\" data-index-in-node=\"20\">how to georeference an image in qgis<\/b>, gather your scanned rasters and reference basemaps.<\/p>\n<p>For this workflow, prepare:<\/p>\n<ul>\n<li>An unreferenced scanned map, preferably PNG, JPG, or TIFF<\/li>\n<li>A QGIS project<\/li>\n<li>A reference layer or basemap with known geographic coordinates<\/li>\n<li>Several identifiable control points<\/li>\n<li>An appropriate CRS for the study area<\/li>\n<\/ul>\n<p>Good control points might include:<\/p>\n<ul>\n<li>Road intersections<\/li>\n<li>Bridges<\/li>\n<li>Building corners<\/li>\n<li>River junctions<\/li>\n<li>Church or railway locations<\/li>\n<li>Survey monuments<\/li>\n<li>Clearly identifiable coastline features<\/li>\n<\/ul>\n<p>For historical maps, choose features that have <strong>not moved significantly over time<\/strong>.<\/p>\n<hr \/>\n<h1><span class=\"ez-toc-section\" id=\"Step_1_Load_the_Basemap_and_Set_the_Project_CRS\"><\/span>Step 1: Load the Basemap and Set the Project CRS<span class=\"ez-toc-section-end\"><\/span><\/h1>\n<p>The first step is to establish a spatial reference framework for the map you are going to georeference. Setting up your reference layer correctly is foundational when learning <b data-path-to-node=\"5,1,1,0\" data-index-in-node=\"73\">how to georeference an image in qgis<\/b>. Matching your reference layer&#8217;s spatial parameters is crucial when learning <b data-path-to-node=\"3,0\" data-index-in-node=\"77\">how to georeference an image in qgis<\/b> effectively.<\/p>\n<h2><span class=\"ez-toc-section\" id=\"11_Open_QGIS\"><\/span>1.1 Open QGIS<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>Start a new QGIS project.<\/p>\n<p>Open:<\/p>\n<p><strong>Project \u2192 New<\/strong><\/p>\n<p>Save the project before beginning.<\/p>\n<p>A useful project structure might be:<\/p>\n<pre><code class=\"language-text\">Historical_Map_Project\/\r\n\u2502\r\n\u251c\u2500\u2500 raw\/\r\n\u2502   \u2514\u2500\u2500 historical_map.jpg\r\n\u2502\r\n\u251c\u2500\u2500 reference\/\r\n\u2502   \u2514\u2500\u2500 roads.gpkg\r\n\u2502\r\n\u251c\u2500\u2500 output\/\r\n\u2502   \u2514\u2500\u2500 historical_map_georeferenced.tif\r\n\u2502\r\n\u2514\u2500\u2500 qgis_project\/<\/code><\/pre>\n<p>Keeping the original scan separate from the processed output makes it easier to reproduce your workflow.<\/p>\n<hr \/>\n<h2><span class=\"ez-toc-section\" id=\"12_Add_a_reference_layer\"><\/span>1.2 Add a reference layer<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>Load a spatial dataset that already has a valid CRS.<\/p>\n<p>For example:<\/p>\n<ul>\n<li>OpenStreetMap-derived roads<\/li>\n<li>Administrative boundaries<\/li>\n<li>Recent satellite imagery<\/li>\n<li>Survey data<\/li>\n<li>Existing GIS vector layers<\/li>\n<\/ul>\n<p>Use:<\/p>\n<p><strong>Layer \u2192 Add Layer<\/strong><\/p>\n<p>Then select your reference dataset.<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter size-large wp-image-684\" src=\"https:\/\/helpwithmygisassignment.com\/blog\/wp-content\/uploads\/2026\/10\/watermarked_img_14887848283700288311-1024x559.jpg\" alt=\"how to georeference an image in qgis adding reference layer\" width=\"1024\" height=\"559\" srcset=\"https:\/\/helpwithmygisassignment.com\/blog\/wp-content\/uploads\/2026\/10\/watermarked_img_14887848283700288311-1024x559.jpg 1024w, https:\/\/helpwithmygisassignment.com\/blog\/wp-content\/uploads\/2026\/10\/watermarked_img_14887848283700288311-300x164.jpg 300w, https:\/\/helpwithmygisassignment.com\/blog\/wp-content\/uploads\/2026\/10\/watermarked_img_14887848283700288311-768x419.jpg 768w, https:\/\/helpwithmygisassignment.com\/blog\/wp-content\/uploads\/2026\/10\/watermarked_img_14887848283700288311.jpg 1408w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><\/p>\n<p>Your reference layer provides the geographic framework against which the scanned map will be aligned.<\/p>\n<hr \/>\n<h2><span class=\"ez-toc-section\" id=\"13_Set_the_project_CRS\"><\/span>1.3 Set the project CRS<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>Check the CRS displayed in the lower-right corner of the QGIS window.<\/p>\n<p>Click the CRS indicator and select the appropriate coordinate reference system.<\/p>\n<p>For example:<\/p>\n<pre><code class=\"language-text\">Project CRS:\r\nEPSG:32637 \u2014 WGS 84 \/ UTM zone 37N<\/code><\/pre>\n<p>The correct CRS depends on your study area and the coordinate system used by your reference data.<\/p>\n<h3><span class=\"ez-toc-section\" id=\"Important_distinction\"><\/span>Important distinction<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>The <strong>project CRS<\/strong> is not necessarily the same thing as the historical map&#8217;s original CRS.<\/p>\n<p>An old map may have been produced using:<\/p>\n<ul>\n<li>A local grid<\/li>\n<li>A national coordinate system<\/li>\n<li>A historical datum<\/li>\n<li>A paper map with no usable coordinate information<\/li>\n<\/ul>\n<p>If the original coordinate system is unknown, you can georeference it using identifiable points from a modern reference dataset.<\/p>\n<hr \/>\n<h1><span class=\"ez-toc-section\" id=\"Step_2_Launch_the_Georeferencer_and_Select_Ground_Control_Points\"><\/span>Step 2: Launch the Georeferencer and Select Ground Control Points<span class=\"ez-toc-section-end\"><\/span><\/h1>\n<p>QGIS includes a dedicated <strong>Georeferencer<\/strong> for assigning geographic coordinates to raster images. When learning <b data-path-to-node=\"14,0,1,0\" data-index-in-node=\"15\">how to georeference an image in qgis<\/b>, selecting reliable ground control points is the most critical step. Understanding where to locate toolbar panels streamlines the overall workflow of <b data-path-to-node=\"5,0\" data-index-in-node=\"82\">how to georeference an image in qgis<\/b>.<\/p>\n<p>Open it from:<\/p>\n<p><strong>Layer \u2192 Georeferencer<\/strong><\/p>\n<p>Depending on your QGIS version, it may appear as:<\/p>\n<p><strong>Layer \u2192 Georeferencer \u2192 Georeferencer<\/strong><\/p>\n<p>or through the <strong>Raster<\/strong> menu.<\/p>\n<hr \/>\n<h2><span class=\"ez-toc-section\" id=\"21_Load_the_scanned_map\"><\/span>2.1 Load the scanned map<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>Inside the Georeferencer window, open your scanned image.<\/p>\n<p>For example:<\/p>\n<pre><code class=\"language-text\">historical_map.jpg<\/code><\/pre>\n<p>[<strong>Insert Screenshot of QGIS Georeferencer with Historical Map Loaded<\/strong>]<\/p>\n<p>The image will initially have no meaningful geographic position.<\/p>\n<p>Your task is to establish a mathematical relationship between:<\/p>\n<p><strong>Image coordinates \u2192 Real-world coordinates<\/strong><\/p>\n<hr \/>\n<h1><span class=\"ez-toc-section\" id=\"What_Are_Ground_Control_Points\"><\/span>What Are Ground Control Points?<span class=\"ez-toc-section-end\"><\/span><\/h1>\n<p>A <strong>ground control point (GCP)<\/strong> is a recognizable location that can be identified both:<\/p>\n<ol>\n<li>On the unreferenced image, and<\/li>\n<li>On a geographically referenced dataset.<\/li>\n<\/ol>\n<p>For example, suppose a historical map contains a distinctive road intersection.<\/p>\n<p>You can click that intersection on the historical map and tell QGIS its corresponding real-world location.<\/p>\n<p>Conceptually:<\/p>\n<pre><code class=\"language-text\">Historical image\r\n       \u2193\r\n   Road junction\r\n       \u2193\r\n      GCP\r\n       \u2193\r\nKnown geographic coordinate\r\n       \u2193\r\nReference map<\/code><\/pre>\n<p>Several GCPs are needed to establish a reliable transformation.<\/p>\n<hr \/>\n<h2><span class=\"ez-toc-section\" id=\"22_Choosing_good_GCPs\"><\/span>2.2 Choosing good GCPs<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>Good GCPs should be:<\/p>\n<ul>\n<li>Clearly identifiable<\/li>\n<li>Distributed across the entire map<\/li>\n<li>Stable through time<\/li>\n<li>Easy to locate precisely<\/li>\n<li>Ideally located near the edges as well as the center<\/li>\n<\/ul>\n<p>Avoid putting all your points in one small area.<\/p>\n<h3><span class=\"ez-toc-section\" id=\"Poor_distribution\"><\/span>Poor distribution<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<pre><code class=\"language-text\">\u250c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2510\r\n\u2502                             \u2502\r\n\u2502                             \u2502\r\n\u2502       \u2022 \u2022 \u2022 \u2022               \u2502\r\n\u2502       \u2022 \u2022 \u2022 \u2022               \u2502\r\n\u2502                             \u2502\r\n\u2514\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2518<\/code><\/pre>\n<h3><span class=\"ez-toc-section\" id=\"Better_distribution\"><\/span>Better distribution<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<pre><code class=\"language-text\">\u250c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2510\r\n\u2502 \u2022                         \u2022 \u2502\r\n\u2502                             \u2502\r\n\u2502                             \u2502\r\n\u2502          \u2022      \u2022           \u2502\r\n\u2502                             \u2502\r\n\u2502 \u2022                         \u2022 \u2502\r\n\u2514\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2518<\/code><\/pre>\n<p>A well-distributed set of GCPs helps the transformation model work across the entire raster rather than only in one region.<\/p>\n<hr \/>\n<h2><span class=\"ez-toc-section\" id=\"23_Add_your_first_GCP\"><\/span>2.3 Add your first GCP<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>Select the <strong>Add Point<\/strong> tool in the Georeferencer.<\/p>\n<p>Click a recognizable location on the scanned map.<\/p>\n<p><a href=\"https:\/\/qgis.org\" target=\"_blank\" rel=\"noopener\">QGIS<\/a> will ask you to enter the corresponding geographic coordinate.<\/p>\n<p>Alternatively, if the reference layer is visible in the main QGIS window, you can obtain the coordinate from the reference dataset.<\/p>\n<p>[<strong>Insert Screenshot of Adding GCPs in QGIS Georeferencer<\/strong>]<\/p>\n<p>Record the point in the GCP table.<\/p>\n<p>A typical table might look like:<\/p>\n<table>\n<thead>\n<tr>\n<th>ID<\/th>\n<th align=\"right\">Image X<\/th>\n<th align=\"right\">Image Y<\/th>\n<th align=\"right\">Map X<\/th>\n<th align=\"right\">Map Y<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>GCP 1<\/td>\n<td align=\"right\">245.2<\/td>\n<td align=\"right\">183.7<\/td>\n<td align=\"right\">36.8219<\/td>\n<td align=\"right\">-1.2921<\/td>\n<\/tr>\n<tr>\n<td>GCP 2<\/td>\n<td align=\"right\">732.5<\/td>\n<td align=\"right\">191.4<\/td>\n<td align=\"right\">36.8512<\/td>\n<td align=\"right\">-1.2875<\/td>\n<\/tr>\n<tr>\n<td>GCP 3<\/td>\n<td align=\"right\">238.7<\/td>\n<td align=\"right\">614.9<\/td>\n<td align=\"right\">36.8194<\/td>\n<td align=\"right\">-1.3267<\/td>\n<\/tr>\n<tr>\n<td>GCP 4<\/td>\n<td align=\"right\">745.1<\/td>\n<td align=\"right\">623.3<\/td>\n<td align=\"right\">36.8531<\/td>\n<td align=\"right\">-1.3214<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>The exact values will depend on your map and CRS.<\/p>\n<hr \/>\n<h2><span class=\"ez-toc-section\" id=\"24_Add_additional_GCPs\"><\/span>2.4 Add additional GCPs<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>Repeat the process for additional recognizable features.<\/p>\n<p>For a simple transformation, use more GCPs than the mathematical minimum.<\/p>\n<p>For example, a first-order polynomial requires at least <strong>three non-collinear points<\/strong>, but using only three points leaves little room to identify errors.<\/p>\n<p>A practical student workflow might use:<\/p>\n<p><strong>6\u201310 well-distributed GCPs<\/strong><\/p>\n<p>rather than relying on the minimum.<\/p>\n<hr \/>\n<h1><span class=\"ez-toc-section\" id=\"Step_3_Choose_Transformation_Settings_and_Understand_RMS_Error\"><\/span>Step 3: Choose Transformation Settings and Understand RMS Error<span class=\"ez-toc-section-end\"><\/span><\/h1>\n<p>Once your GCPs are established, configure the transformation.<\/p>\n<p>Open the transformation settings in the Georeferencer.<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignright wp-image-688 size-full\" src=\"https:\/\/helpwithmygisassignment.com\/blog\/wp-content\/uploads\/2026\/10\/ba135a7a-8f37-4ee4-8ccf-270dd3607c91-1.jpg\" alt=\"QGIS Georeferencer Transformation Settings dialog box showing Transformation Type, Resampling Method, and Target CRS\" width=\"1024\" height=\"559\" srcset=\"https:\/\/helpwithmygisassignment.com\/blog\/wp-content\/uploads\/2026\/10\/ba135a7a-8f37-4ee4-8ccf-270dd3607c91-1.jpg 1024w, https:\/\/helpwithmygisassignment.com\/blog\/wp-content\/uploads\/2026\/10\/ba135a7a-8f37-4ee4-8ccf-270dd3607c91-1-300x164.jpg 300w, https:\/\/helpwithmygisassignment.com\/blog\/wp-content\/uploads\/2026\/10\/ba135a7a-8f37-4ee4-8ccf-270dd3607c91-1-768x419.jpg 768w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><\/p>\n<p>Important settings include:<\/p>\n<ul>\n<li>Transformation type<\/li>\n<li>Resampling method<\/li>\n<li>Target CRS<\/li>\n<li>Output raster<\/li>\n<li>Output format<\/li>\n<li>GCP options<\/li>\n<\/ul>\n<hr \/>\n<h1><span class=\"ez-toc-section\" id=\"Polynomial_1_vs_Thin_Plate_Spline\"><\/span>Polynomial 1 vs Thin Plate Spline<span class=\"ez-toc-section-end\"><\/span><\/h1>\n<p>The transformation model determines how QGIS converts the original image coordinates into geographic coordinates A common question when studying <b data-path-to-node=\"14,1,1,0\" data-index-in-node=\"33\">how to georeference an image in qgis<\/b> is whether to use Polynomial 1 or Thin Plate Spline.<\/p>\n<h2><span class=\"ez-toc-section\" id=\"Polynomial_1\"><\/span>Polynomial 1<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>A <strong>first-order polynomial transformation<\/strong> is often appropriate when the scanned map mainly needs:<\/p>\n<ul>\n<li>Translation<\/li>\n<li>Rotation<\/li>\n<li>Scaling<\/li>\n<li>Skewing<\/li>\n<\/ul>\n<p>It treats the transformation relatively simply.<\/p>\n<p>Conceptually:<\/p>\n<pre><code class=\"language-text\">Original image\r\n      \u2193\r\nScale + Rotate + Shift\r\n      \u2193\r\nGeoreferenced image<\/code><\/pre>\n<p>This is often a sensible starting point for a scanned map that has not suffered significant physical deformation.<\/p>\n<h3><span class=\"ez-toc-section\" id=\"Use_Polynomial_1_when\"><\/span>Use Polynomial 1 when:<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<ul>\n<li>The map is relatively rigid.<\/li>\n<li>Distortion is limited.<\/li>\n<li>The map has a consistent scale.<\/li>\n<li>You want a relatively simple transformation.<\/li>\n<\/ul>\n<hr \/>\n<h1><span class=\"ez-toc-section\" id=\"Thin_Plate_Spline\"><\/span>Thin Plate Spline<span class=\"ez-toc-section-end\"><\/span><\/h1>\n<p><strong>Thin Plate Spline (TPS)<\/strong> is a more flexible transformation.<\/p>\n<p>It can accommodate local distortions that a simple polynomial transformation cannot model effectively.<\/p>\n<p>This can be useful for historical maps that have:<\/p>\n<ul>\n<li>Paper stretching<\/li>\n<li>Folding<\/li>\n<li>Local deformation<\/li>\n<li>Uneven scanning<\/li>\n<li>Other spatial distortions<\/li>\n<\/ul>\n<p>Conceptually:<\/p>\n<pre><code class=\"language-text\">Historical map\r\n~~~~~~~~~~~~~~\r\n  irregular shape\r\n       \u2193\r\nThin Plate Spline\r\n       \u2193\r\nFlexible geographic alignment<\/code><\/pre>\n<p>However, flexibility is not automatically better.<\/p>\n<p>A highly flexible transformation can produce unexpected local distortions if your GCPs are inaccurate or poorly distributed.<\/p>\n<hr \/>\n<h1><span class=\"ez-toc-section\" id=\"Understanding_RMS_Error\"><\/span>Understanding RMS Error<span class=\"ez-toc-section-end\"><\/span><\/h1>\n<p>The <strong>RMS (Root Mean Square) error<\/strong> provides a numerical measure of how closely the transformation fits your control points.<\/p>\n<p>A simplified interpretation is:<\/p>\n<blockquote><p>How far, on average, the transformed GCP locations differ from their target positions according to the transformation model.<\/p><\/blockquote>\n<p>A lower RMS error generally indicates a closer mathematical fit to the selected control points.<\/p>\n<p>However:<\/p>\n<p><strong>A low RMS error does not automatically mean the georeferencing is geographically correct.<\/strong><\/p>\n<p>For example, if several GCPs were incorrectly identified but consistently placed in the wrong locations, the transformation can still produce an apparently good numerical fit.<\/p>\n<p>Therefore, evaluate:<\/p>\n<ol>\n<li>RMS error<\/li>\n<li>GCP placement<\/li>\n<li>GCP distribution<\/li>\n<li>Visual alignment with independent reference data<\/li>\n<\/ol>\n<hr \/>\n<h2><span class=\"ez-toc-section\" id=\"Dont_blindly_minimize_RMS_error\"><\/span>Don&#8217;t blindly minimize RMS error<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>Suppose you have:<\/p>\n<pre><code class=\"language-text\">GCP 1 \u2192 0.8\r\nGCP 2 \u2192 1.1\r\nGCP 3 \u2192 0.7\r\nGCP 4 \u2192 12.5<\/code><\/pre>\n<p>The fourth point deserves investigation.<\/p>\n<p>It could represent:<\/p>\n<ul>\n<li>An incorrectly clicked location<\/li>\n<li>A feature that changed position<\/li>\n<li>A coordinate-entry mistake<\/li>\n<li>A poor-quality reference point<\/li>\n<li>Genuine historical map distortion<\/li>\n<\/ul>\n<p>Don&#8217;t automatically delete the point simply because it increases RMS error.<\/p>\n<p>First determine <strong>why<\/strong> it differs.<\/p>\n<hr \/>\n<h1><span class=\"ez-toc-section\" id=\"Step_4_Generate_and_Verify_the_GeoTIFF\"><\/span>Step 4: Generate and Verify the GeoTIFF<span class=\"ez-toc-section-end\"><\/span><\/h1>\n<p>Once the transformation settings and GCPs are satisfactory, specify the output file.<\/p>\n<p>A recommended output format is <strong>GeoTIFF (<code>.tif<\/code>)<\/strong> because it can store geographic referencing information alongside the raster data.<\/p>\n<p>For example:<\/p>\n<pre><code class=\"language-text\">historical_map_georeferenced.tif<a id=\"category-add-toggle\" class=\"hide-if-no-js taxonomy-add-new\" href=\"https:\/\/helpwithmygisassignment.com\/blog\/wp-admin\/post.php?post=432&amp;action=edit#category-add\"> + Add Category <\/a><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter size-large wp-image-686\" src=\"https:\/\/helpwithmygisassignment.com\/blog\/wp-content\/uploads\/2026\/10\/watermarked_img_3412201022971567038-1024x709.jpg\" alt=\"QGIS Georeferencer Transformation Settings window for configuring target CRS and output raster parameters\" width=\"1024\" height=\"709\" srcset=\"https:\/\/helpwithmygisassignment.com\/blog\/wp-content\/uploads\/2026\/10\/watermarked_img_3412201022971567038-1024x709.jpg 1024w, https:\/\/helpwithmygisassignment.com\/blog\/wp-content\/uploads\/2026\/10\/watermarked_img_3412201022971567038-300x208.jpg 300w, https:\/\/helpwithmygisassignment.com\/blog\/wp-content\/uploads\/2026\/10\/watermarked_img_3412201022971567038-768x532.jpg 768w, https:\/\/helpwithmygisassignment.com\/blog\/wp-content\/uploads\/2026\/10\/watermarked_img_3412201022971567038.jpg 1247w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><\/code><\/pre>\n<p>&nbsp;<\/p>\n<p>Set the appropriate target CRS.<\/p>\n<p>Then start the georeferencing process.<\/p>\n<p>QGIS will create the transformed raster. Selecting the correct transformation algorithm ensures high geometric precision throughout your <b data-path-to-node=\"9,0\" data-index-in-node=\"97\">how to georeference an image in qgis<\/b> workflow.<\/p>\n<hr \/>\n<h1><span class=\"ez-toc-section\" id=\"41_Load_the_output_into_QGIS\"><\/span>4.1 Load the output into QGIS<span class=\"ez-toc-section-end\"><\/span><\/h1>\n<p>Add the resulting GeoTIFF to your main QGIS project.<\/p>\n<p>You should now see the historical map positioned geographically.<\/p>\n<p>For example:<\/p>\n<pre><code class=\"language-text\">Modern reference layer\r\n\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\r\n\r\n     Roads\r\n       \u2502\r\n   \u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\r\n       \u2502\r\nHistorical map\r\n\u2588\u2588\u2588\u2588\u2588\u2588\u2588\u2588\u2588\u2588\u2588\u2588\u2588\u2588\u2588\u2588\r\n\u2588\u2588\u2588\u2588\u2588\u2588\u2588\u2588\u2588\u2588\u2588\u2588\u2588\u2588\u2588\u2588<\/code><\/pre>\n<p>The historical map should align with recognizable features in your reference data.<\/p>\n<hr \/>\n<h1><span class=\"ez-toc-section\" id=\"42_Verify_alignment_visually\"><\/span>4.2 Verify alignment visually<span class=\"ez-toc-section-end\"><\/span><\/h1>\n<p>Zoom into several locations.<\/p>\n<p>Don&#8217;t inspect only the center of the map.<\/p>\n<p>Check:<\/p>\n<h3><span class=\"ez-toc-section\" id=\"Center\"><\/span>Center<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>Does the historical feature align with the modern feature?<\/p>\n<h3><span class=\"ez-toc-section\" id=\"Edges\"><\/span>Edges<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>Does the alignment remain reasonable near the map boundaries?<\/p>\n<h3><span class=\"ez-toc-section\" id=\"Corners\"><\/span>Corners<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>Do features near the corners remain geographically plausible?<\/p>\n<h3><span class=\"ez-toc-section\" id=\"Independent_features\"><\/span>Independent features<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>Where possible, check features that were <strong>not used as GCPs<\/strong>.<\/p>\n<p>This is particularly important because evaluating the same points used to calculate the transformation can give an overly optimistic impression of accuracy.<\/p>\n<hr \/>\n<h1><span class=\"ez-toc-section\" id=\"Troubleshooting_Common_Georeferencing_Problems\"><\/span>Troubleshooting Common Georeferencing Problems<span class=\"ez-toc-section-end\"><\/span><\/h1>\n<h2><span class=\"ez-toc-section\" id=\"Problem_1_RMS_Error_Is_Too_High\"><\/span>Problem 1: RMS Error Is Too High<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>A high RMS error can result from several causes. Managing root mean square (RMS) error values resolves common spatial alignment issues when practicing <b data-path-to-node=\"11,0\" data-index-in-node=\"103\">how to georeference an image in qgis<\/b>.<\/p>\n<h3><span class=\"ez-toc-section\" id=\"Check_your_GCPs\"><\/span>Check your GCPs<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>Look for:<\/p>\n<ul>\n<li>Incorrect coordinates<\/li>\n<li>Misidentified features<\/li>\n<li>Points clicked too far from the actual feature<\/li>\n<li>Features that changed location<\/li>\n<li>Poor point distribution<\/li>\n<\/ul>\n<p>Start by checking the GCP with the largest residual error.<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter size-large wp-image-685\" src=\"https:\/\/helpwithmygisassignment.com\/blog\/wp-content\/uploads\/2026\/10\/watermarked_img_15825717162598157827-1024x559.jpg\" alt=\"QGIS Georeferencer GCP table showing high residual errors during map georeferencing troubleshooting\" width=\"1024\" height=\"559\" srcset=\"https:\/\/helpwithmygisassignment.com\/blog\/wp-content\/uploads\/2026\/10\/watermarked_img_15825717162598157827-1024x559.jpg 1024w, https:\/\/helpwithmygisassignment.com\/blog\/wp-content\/uploads\/2026\/10\/watermarked_img_15825717162598157827-300x164.jpg 300w, https:\/\/helpwithmygisassignment.com\/blog\/wp-content\/uploads\/2026\/10\/watermarked_img_15825717162598157827-768x419.jpg 768w, https:\/\/helpwithmygisassignment.com\/blog\/wp-content\/uploads\/2026\/10\/watermarked_img_15825717162598157827.jpg 1408w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><\/p>\n<p>If you discover that the point was incorrectly placed, correct it and recalculate the transformation.<\/p>\n<hr \/>\n<h2><span class=\"ez-toc-section\" id=\"Problem_2_The_Map_Is_Correct_in_the_Center_but_Wrong_at_the_Edges\"><\/span>Problem 2: The Map Is Correct in the Center but Wrong at the Edges<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>This often indicates that the selected transformation does not adequately represent the raster&#8217;s spatial distortion.<\/p>\n<p>Possible causes include:<\/p>\n<ul>\n<li>Insufficient GCPs<\/li>\n<li>Poor GCP distribution<\/li>\n<li>Map stretching<\/li>\n<li>Historical paper deformation<\/li>\n<li>An unsuitable transformation model<\/li>\n<\/ul>\n<p>Try adding well-distributed GCPs near the problematic areas.<\/p>\n<p>You can also compare a first-order polynomial with a more flexible transformation such as Thin Plate Spline.<\/p>\n<hr \/>\n<h1><span class=\"ez-toc-section\" id=\"Problem_3_The_Entire_Map_Is_Shifted\"><\/span>Problem 3: The Entire Map Is Shifted<span class=\"ez-toc-section-end\"><\/span><\/h1>\n<p>If the map has approximately the correct shape but is consistently displaced, check:<\/p>\n<ul>\n<li>Target CRS<\/li>\n<li>Coordinate values<\/li>\n<li>Reference layer CRS<\/li>\n<li>Project CRS<\/li>\n<li>GCP coordinate entry<\/li>\n<\/ul>\n<p>A CRS mismatch can produce a large positional displacement even when the image itself is perfectly fine.<\/p>\n<hr \/>\n<h1><span class=\"ez-toc-section\" id=\"Problem_4_The_Raster_Is_Severely_Warped\"><\/span>Problem 4: The Raster Is Severely Warped<span class=\"ez-toc-section-end\"><\/span><\/h1>\n<p>If the output looks dramatically distorted:<\/p>\n<ol>\n<li>Check for incorrectly positioned GCPs.<\/li>\n<li>Check whether GCPs are concentrated in one area.<\/li>\n<li>Reduce unnecessary transformation complexity.<\/li>\n<li>Try Polynomial 1 as a baseline.<\/li>\n<li>Verify that the target CRS is appropriate.<\/li>\n<li>Check whether historical features have changed position.<\/li>\n<\/ol>\n<p>Do not assume that Thin Plate Spline will automatically fix a poorly controlled dataset.<\/p>\n<hr \/>\n<h1><span class=\"ez-toc-section\" id=\"Problem_5_Control_Points_Are_in_the_Wrong_Places\"><\/span>Problem 5: Control Points Are in the Wrong Places<span class=\"ez-toc-section-end\"><\/span><\/h1>\n<p>A misplaced GCP can have a significant effect on the transformation.<\/p>\n<p>For example, suppose the actual road intersection is:<\/p>\n<pre><code class=\"language-text\">        \u2502\r\n\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\r\n        \u2502<\/code><\/pre>\n<p>but the GCP is placed several pixels away:<\/p>\n<pre><code class=\"language-text\">        \u2502\r\n\u2500\u2500\u2500\u2500\u2022\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\r\n        \u2502<\/code><\/pre>\n<p>The transformation receives incorrect information about the relationship between image and geographic coordinates.<\/p>\n<h3><span class=\"ez-toc-section\" id=\"Solution\"><\/span>Solution<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>Zoom in before placing the GCP.<\/p>\n<p>For small features, use a high magnification level so you can click as close as possible to the exact location.<\/p>\n<hr \/>\n<h1><span class=\"ez-toc-section\" id=\"Problem_6_Historical_Features_Have_Changed\"><\/span>Problem 6: Historical Features Have Changed<span class=\"ez-toc-section-end\"><\/span><\/h1>\n<p>This is especially important when georeferencing historical maps.<\/p>\n<p>A road intersection, river channel, shoreline, or building may have changed since the map was produced.<\/p>\n<p>For example:<\/p>\n<pre><code class=\"language-text\">Historical map:\r\n\r\nRiver\r\n~~~~~~~\r\n     \\\r\n      \\\r\n\r\nModern map:\r\n\r\nRiver\r\n~~~~~~\r\n      \\\r\n       \\<\/code><\/pre>\n<p>If you use the modern river location as a GCP for a historical river that has migrated, you introduce an error into the transformation.<\/p>\n<p>Whenever possible, choose <strong>stable landmarks<\/strong>.Mastering <b data-path-to-node=\"14,2,1,0\" data-index-in-node=\"11\">how to georeference an image in qgis<\/b> ensures accurate spatial alignment for unreferenced historical maps.<\/p>\n<h1><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter wp-image-474 size-full\" src=\"https:\/\/helpwithmygisassignment.com\/blog\/wp-content\/uploads\/2026\/10\/9a76f9d3-7fb0-4795-aeb2-c88b47050cb5.jpg\" alt=\"how to georeference an image in qgis step by step workflow diagram\" width=\"1024\" height=\"828\" srcset=\"https:\/\/helpwithmygisassignment.com\/blog\/wp-content\/uploads\/2026\/10\/9a76f9d3-7fb0-4795-aeb2-c88b47050cb5.jpg 1024w, https:\/\/helpwithmygisassignment.com\/blog\/wp-content\/uploads\/2026\/10\/9a76f9d3-7fb0-4795-aeb2-c88b47050cb5-300x243.jpg 300w, https:\/\/helpwithmygisassignment.com\/blog\/wp-content\/uploads\/2026\/10\/9a76f9d3-7fb0-4795-aeb2-c88b47050cb5-768x621.jpg 768w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><\/h1>\n<hr \/>\n<h1><span class=\"ez-toc-section\" id=\"Recommended_GCP_Strategy\"><\/span>Recommended GCP Strategy<span class=\"ez-toc-section-end\"><\/span><\/h1>\n<p>For a student historical-map project, use a workflow such as:<\/p>\n<pre><code class=\"language-text\">1. Identify stable features\r\n          \u2193\r\n2. Distribute GCPs across the map\r\n          \u2193\r\n3. Add 6\u201310+ GCPs\r\n          \u2193\r\n4. Start with Polynomial 1\r\n          \u2193\r\n5. Inspect RMS\/residuals\r\n          \u2193\r\n6. Correct obvious GCP errors\r\n          \u2193\r\n7. Compare alternative transformations if necessary\r\n          \u2193\r\n8. Export GeoTIFF\r\n          \u2193\r\n9. Validate against independent reference features<\/code><\/pre>\n<p>The exact number of GCPs should depend on the map, transformation model, spatial distortion, and intended accuracy.<\/p>\n<hr \/>\n<h1><span class=\"ez-toc-section\" id=\"Georeferencing_Checklist\"><\/span>Georeferencing Checklist<span class=\"ez-toc-section-end\"><\/span><\/h1>\n<p>Before submitting your <a href=\"https:\/\/helpwithmygisassignment.com\">GIS assignment<\/a> or research dataset, check:<\/p>\n<table>\n<thead>\n<tr>\n<th>Check<\/th>\n<th>Question<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td><strong>Reference CRS<\/strong><\/td>\n<td>Is the target CRS correct?<\/td>\n<\/tr>\n<tr>\n<td><strong>GCP quality<\/strong><\/td>\n<td>Are the points clearly identifiable?<\/td>\n<\/tr>\n<tr>\n<td><strong>GCP distribution<\/strong><\/td>\n<td>Are they spread across the entire map?<\/td>\n<\/tr>\n<tr>\n<td><strong>GCP accuracy<\/strong><\/td>\n<td>Were points placed precisely?<\/td>\n<\/tr>\n<tr>\n<td><strong>Transformation<\/strong><\/td>\n<td>Is the selected model appropriate?<\/td>\n<\/tr>\n<tr>\n<td><strong>RMS error<\/strong><\/td>\n<td>Are unusually large residuals investigated?<\/td>\n<\/tr>\n<tr>\n<td><strong>Visual alignment<\/strong><\/td>\n<td>Does the map align with independent reference data?<\/td>\n<\/tr>\n<tr>\n<td><strong>Output<\/strong><\/td>\n<td>Was the result saved as a GeoTIFF?<\/td>\n<\/tr>\n<tr>\n<td><strong>Metadata<\/strong><\/td>\n<td>Have CRS, GCPs, transformation, and source information been documented?<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<hr \/>\n<h1><span class=\"ez-toc-section\" id=\"Quick_Reference_Historical_Map_Georeferencing_in_QGIS\"><\/span>Quick Reference: Historical Map Georeferencing in QGIS<span class=\"ez-toc-section-end\"><\/span><\/h1>\n<blockquote>\n<h3><span class=\"ez-toc-section\" id=\"%EF%B8%8F_Image_%E2%86%92_GCPs_%E2%86%92_Transformation_%E2%86%92_GeoTIFF_%E2%86%92_Validation\"><\/span>\ufe0f <strong>Image \u2192 GCPs \u2192 Transformation \u2192 GeoTIFF \u2192 Validation<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p><strong>1. Load reference data<\/strong><br \/>\nEstablish the geographic framework and appropriate CRS.<\/p>\n<p><strong>2. Open Georeferencer<\/strong><br \/>\nLoad the scanned historical map.<\/p>\n<p><strong>3. Add GCPs<\/strong><br \/>\nMatch recognizable locations on the scan to known geographic coordinates.<\/p>\n<p><strong>4. Choose transformation<\/strong><br \/>\nStart with <strong>Polynomial 1<\/strong> for relatively rigid maps; consider <strong>Thin Plate Spline<\/strong> for genuine local deformation.<\/p>\n<p><strong>5. Evaluate RMS error<\/strong><br \/>\nInvestigate large residuals rather than simply trying to minimize the number.<\/p>\n<p><strong>6. Generate GeoTIFF<\/strong><br \/>\nSave the transformed raster with its spatial reference information.<\/p>\n<p><strong>7. Validate<\/strong><br \/>\nCompare the result against independent reference features across the entire map.<\/p>\n<p><strong>Key principle:<\/strong> A low RMS error is useful, but <strong>accurate GCP identification, good spatial distribution, an appropriate transformation, and independent visual validation are equally important<\/strong>.<\/p><\/blockquote>\n<p>Georeferencing is therefore not simply a matter of making an old map &#8220;fit&#8221; a modern basemap. It is a spatial transformation process in which the quality of the final dataset depends heavily on the quality and distribution of the <strong>ground control points<\/strong>, the chosen transformation model, and the validation procedure.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>How to Georeference an Image in QGIS: A Complete Step-by-Step Workflow Georeferencing assigns real-world geographic coordinates to an image that does not already contain spatial reference information. In this guide, you will learn how to georeference an image in QGIS using a scanned historical map, CAD print, aerial photograph, or other unreferenced raster. The process &#8230; <a title=\"ow to Georeference an Image in QGIS: 7 Easy Steps\" class=\"read-more\" href=\"https:\/\/helpwithmygisassignment.com\/blog\/georeference-image-in-qgis\/\" aria-label=\"Read more about ow to Georeference an Image in QGIS: 7 Easy Steps\">Read more<\/a><\/p>\n","protected":false},"author":1,"featured_media":684,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[5,4],"tags":[],"class_list":["post-432","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-general-articles","category-gis-articles"],"_links":{"self":[{"href":"https:\/\/helpwithmygisassignment.com\/blog\/wp-json\/wp\/v2\/posts\/432","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/helpwithmygisassignment.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/helpwithmygisassignment.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/helpwithmygisassignment.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/helpwithmygisassignment.com\/blog\/wp-json\/wp\/v2\/comments?post=432"}],"version-history":[{"count":5,"href":"https:\/\/helpwithmygisassignment.com\/blog\/wp-json\/wp\/v2\/posts\/432\/revisions"}],"predecessor-version":[{"id":689,"href":"https:\/\/helpwithmygisassignment.com\/blog\/wp-json\/wp\/v2\/posts\/432\/revisions\/689"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/helpwithmygisassignment.com\/blog\/wp-json\/wp\/v2\/media\/684"}],"wp:attachment":[{"href":"https:\/\/helpwithmygisassignment.com\/blog\/wp-json\/wp\/v2\/media?parent=432"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/helpwithmygisassignment.com\/blog\/wp-json\/wp\/v2\/categories?post=432"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/helpwithmygisassignment.com\/blog\/wp-json\/wp\/v2\/tags?post=432"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}