Height data must be obtained using AirPhoto. With a map calibrated in one of the supported national or international grid systems displayed, click on the DTM/Heights menu item:
A drop-down menu in AirPhoto displays various options:
You can add heights manually using the contour lines of a displayed map, or if available you can import heights from various national and international sources. The option import NTF heights will be visible if you have loaded a maps from the UK. Heights need not be at regular intervals, regardless of the source. Many national mapping agencies offer height data in various proprietary formats which not are supported by AirPhoto. CSV format (comma separated variable) format can be read by AirPhoto and by most spreadsheet programmes.
If you don't have external height data, you can add it manually fairly quickly if the map has contour lines. Click on Add or press F7 to start the process.
A magnifying window appears which should be centered over a contour line. A left mouse click brints up a dialog box and the height of the contour can be entered:
The height point will then be recorded on the line:
Height points should be entered only where contours undergo significant changes in direction. When you have entered the first value on a given line, this value will be retained for the next point, so that you only need to change it when you move to another contour height. It is not necessary to enter heights for all contours. Major height changes, e.g. at 5 or 10 meter intervals should be used. Intermediate height contours may be ignored. For moderately hilly areas, between 30 and 100 height points should usually be sufficient to describe the terrain accurately enough.
Save the height data in AirPhoto explicitly from the DTM/Heights menu or by closing the map image normally. Make sure that the name of the height file is the same as that of the map or AirPhoto3D won't find it. AirPhoto height files are in binary format and can only be created and data imported or entered in AirPhoto itself. This version of AirPhoto3D does not load other formats.