The processing process is fully automatic, except for the optional step of measuring the support points, and consists of the following steps:

• creation of the project;
• orientation;
• measurement of support points;
• creation of a dense cloud of points;
• creation of a matrix of heights;
• creation of an orthophotomap.

At the first stage, a PPH project file is created and the names of photos from the project folder and all subfolders are entered into it. The file must be created in the folder containing the photos selected for processing.

After pressing the "Execute" button in the orientation dialog, the following main steps are performed:

• 1. Measurement of points - search of especial points in the image and encoding them with a descriptor - a digital sequence that describes the colors of pixels in the nearest environment.
• 2. Linking images - search of points on images corresponding to one point of the terrain.
• 3. Preliminary orientation - sequential joining of images to the first image of the block, selected by the maximum number of links.
• 4. Creation of a sparse point cloud - calculation of coordinates of points found on at least three images and their rejection by discrepancies in triplets.
• 5. Equalization - minimization of discrepancies of points on images. During the equalization process, images orientation elements, coordinates of cloud's points and elements of interior orientation are refined.

Mode of measurement of support points

Orientation by support points is not necessary if the images contain the coordinates of the photographing points. In this case, the orientation accuracy will be of the order of several meters. Support points should be written into a text file line by line in the format Point_number X Y Z. For orientation, 3 points are enough, but for a reliable assessment of accuracy, at least 10 points, evenly spaced in the survey area, are required.

After measuring 3 points on at least two images, the parameters of recalculation to the specified coordinate system are calculated. According to the results of the calculation, the table of discrepancies on the points is filled in and the root-mean-square error of orientation is calculated.

Creating a matrix of heights

The matrix of heights is created on the basis of the cloud of points built at the previous stage of processing, and is necessary for the next stage of creating an orthophotomap. After creation the matrix of heights is written into a project folder. Displaying the created matrix of heights in the program is not provided, it can be viewed and used as an independent product in the GIS Panorama in the Complex of 3D analysis.