How to georeference an image


GeoResGlobe contains state-wide mosaic of imagery across Queensland, collected from various platforms such as satellites, piloted aircraft, and drones. This imagery is georeferenced meaning it is matched to real locations on the ground.

Whilst this imagery is suitable for many mapping applications, in some circumstance you may wish to add a different image to your map: to use as a backdrop, highlight certain features, or show a site at an earlier point in time, for example with an unreferenced historical image obtained with the Past Imagery Tool.

To get started, first log in to GeoResGlobe using one of the available options. This will allow you to save your changes once your image is registered. If necessary, first click Sign Up to create an account.

login button

login signup

Zoom to the approximate location of your image.

Click Layers --> Add My Data and add either a either a .jpg or png file (maximum 3.5 Mb and 7 Mb respectively)

Layers button

add my data

drag and drop data

The image now appears in your Layers list, and is centred on-screen.

The Georeferencing Toolbar will also open, for you to manually register your image.

In the Layers panel, click the right arrow next to your image layer and adjust the opacity so you can see other features on the map that you can refer to (eg a topographic base map)

image layer

layer opacity

If necessary, click on the Centre Image to centre your image on the screen.

centre image

centred image

Then click Adjust position.

georeferencing

Click inside the image and drag the mouse to move the image around the screen.

georeferencing

Click on the corner handles to adjust the size.

georeferencing

georeferencing

Click the rotation handle to rotate the image if needed.

georeferencing

georeferencing

If you are not happy with your changes, click the Reset Image tool to start again.

georeferencing

Otherwise, click Save Image to save your changes.

georeferencing

Now use the Add Control Point tool to match your image to points on your underlying map

georeferencing

Click on Add Control Point and click on the desired location on you image (if you are unhappy with where you clicked, hit the escape key to cancel the operation and start again) then click again, this time on the corresponding feature on the map.

georeferencing

Continue adding control points. If you are unhappy with any of your points, remove them with the Delete Control Point tool.

georeferencing

If you wish to begin again, click Reset Image to revert to its previous saved state. Otherwise click Save Image to complete georeferencing.

georeferencing

Then close the Georeferencing Toolbar

georeferencing

To re-open the toolbar, at any time, go to the layers panel and click the arrow next to your registered image. Then select the Georeference Image option and adjust your image as needed.

georeferencing

georeferencing

Note: that the georeferenced image will only be retained as long as your mapping session is open. If you wish to retain the image for ongoing use, it is recommend you save it into a map including user data.

For full details on saving maps, refer to the tutorial video on Printing, Saving and Sharing maps.

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You can also download your georeferenced image for use in other mapping applications, using the Download Image option. Follow the Readme.txt instructions included in the downloaded file for instructions on using the downloaded image.

georeferencing

How to upload a georeferenced image


Georeferenced images can be loaded into GeoResGlobe to compare against other map layers. Supported images include png or jpg with world file coordinates projected to WGS84 Web Mercator (Auxiliary Sphere). The image must be zipped with the world file coordinates and you must be logged in prior to uploading the file.

To add a georeferenced image to GeoResGlobe:

Login to GeoResGlobe using the Login or Sign Up button in the top right of the screen.

Login button

Select the Layers button

layers button

Click on the Add My Data button at the bottom of the Layers panel

add my data

Drag and drop or browse to the zipped png or jpg with world file.

drag and drop data

The image will load into the map. A popup will display to let you know that the GeoReferencing toolbar can be used to adjust the position of the image. See How to georeference an image for more information on how to use this toolbar.