Terrain images are uploaded images that gets textured on the terrain model. Useful to overlay smaller area maps or illustration on the ground. File formats are PNG, JPG and GIF.
To upload, click the plus icon or drag and drop images from the harddrive on the upload window or anywhere in the project view. After upload, the image is selected and the properties window for the image opens.
You can set the position, rotation and dimension either by using the object tool in the 3D-world or by entering values into textfields using the Geospatial settings page.
The inspector subpage shows file size and resolution of the uploaded image. Try not to use to high resolution images because it impacts the performance of the 3D-rendering.