This tool can be used to locate the principal point in an aerial photograph based on four or eight digitized fiducial marks. A fiducial mark is a visible marker placed at the corners and/or the side mid-points of an aerial photograph and are used for photogrammetric analyses. The user must specify the name of the fiducial mark vector file, which must be a shapefile of a POINT ShapeType. The output file will contain the single vector point situated at the intersection of the two or four lines connecting opposing fiducial marks. Note that if all eight fiducial marks are provided (i.e. the four corners and four side mid-points) then the principal point is estimated as the average location of the intersections of the two sets of two lines connecting opposing principal points (one set connecting corners and another connecting side mid-points).
The following is an example of a Python script that uses this tool:
wd = pluginHost.getWorkingDirectory()
inputFile = wd + "input.shp"
outputFile = wd + "output.shp"
args = [inputFile, outputFile]
pluginHost.runPlugin("LocatePrincipalPoint", args, False)
This is a Groovy script also using this tool:
def wd = pluginHost.getWorkingDirectory()
def inputFile = wd + "input.shp"
def outputFile = wd + "output.shp"
String[] args = [inputFile, outputFile]
pluginHost.runPlugin("LocatePrincipalPoint", args, false)