Image Georeferencing

Zoom, Stretch, Rotate, Scale!

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Tag

If your image contains no white space, margins, borders etc, simply click Continue without Cropping.
Your image is displayed with a movable rectangle inside. Move the handles at each corner until you have cropped (removed) any components that are not part of the map.
Drag the cropping area to another part of the map if required.
You can change the background colour (ie the uncropped image). This may help as you adjust borders.
You can also change the background opacity.
Preview lets you see the cropped image prior to the next step.

Your map can now be zoomed into to show all features.
For best fit, identify 4 points at each corner - give us a trench map reference or lat, lon.
The closer you get to the boundary, the more accurate our initial position is.
Optionally, give us one of the following:

At least 2 corner points.
Minimum of 3 points on the map, such as a church, cross-road or chapel.
One 500 yard line and a north / south line (for sketch map, aerial photograph or non-standard map extract.

Every option allows you to type in a name, such as Minden. We will search the Gazetteer and find the lat, lon for Minden Post.
You will need to select the most appropriate entry for a generic term such as salient.

We display a modern map, your overlay & tools to move, rotate, zoom, combo-zoom-rotate and rubbersheet.
Initially we lock the image so you can assess the initial fit.
We recommend you use the rubbersheet last — it is so easy to overstretch and end up with a distorted image impossible to unravel!
Try this sequence:

You can change the opacity of your image at any stage.
There is a shortcut to rotate and zoom at the same time — note the warnings above and don't get lost or dizzy!
When finished, lock the image so that you don't accidentally drag it somewhere else.

Toolbar Options

Time spent determining the exact corners will guide how close our initial fit is.
If you put the corner in as a trench map reference, such as 57c.J.16.b.3.1, then we will calculate the latitude and longitude for you.

We use utilities from original Copyrighted Material or as licensed under Creative Commons or similar

Step 3 uses Gazetteer of the Western Front, originally courtesy of John Reed, updated 2016 - 2020. Used under license.
Step 3 uses Trench Names from tMapper, original source hand scanned maps.
Step 3 & 4 uses Leaflet — an open-source library for mobile-friendly interactive maps.
Step 4 uses Williams Aviation Formulary, but sources an implementation of Destination point given distance and bearing from start point.
Step 4 uses Distortable Image library for Leaflet, part of Public Labs' MapKnitter support.
Step 4 uses GD Library — dynamic creation and editing of images.