What is the difference between real orthophoto and traditional orthophoto?

Because of the central projection, the aerial image will cover the scene of the facade building. According to the orthophoto map of DEM, this occlusion phenomenon cannot be eliminated. This is a traditional orthophoto image. This problem does not exist in real shooting. It seems that the real shot image is projected from the top of each object. If you want to shoot a real shot, there are very strict requirements from the venue. The width of the flight belt should be very narrow and the overlap should be large. Moreover, when processing indoor data, the point cloud should be edited strictly by people to generate DSM for orthorectification.

Compared with the correction method and building effect, the characteristics of traditional DOM are as follows:

Corrected by DEM

Will produce a sloping building

There will be shielding caused by high-rise buildings.

The real DOM features are as follows:

Corrected by DSM

The building is completely vertical, and everything in the picture looks down vertically.

Unshielded phenomenon