One method of establishing the accuracy of your project is to use "check distances". You will need to obtain measurements for several items in a scene and compare these measurements with the measurements obtained from your PhotoModeler project.
For example: If you are measuring a road scene, and you need to determine the length of a set of skid marks, there may be a stop sign, the corner of an ambulance and a section of guard rail visible in 3 of your photographs. You visit the accident scene with a tape measure and measure the length of the guard rail and the height of the stop sign. You also determine from the manufacturer the height of the box on the ambulance. You then use PhotoModeler to measure these items and also the length of the skid marks.
|
Item |
Tape measure |
PhotoModeler measurement |
Difference |
% |
|
stop sign |
6.78' |
6.73' |
0.05' |
0.7% |
|
guard rail |
10.2' |
10.09' |
0.11' |
1.0% |
|
height of ambulance |
6.3' |
6.21' |
0.09' |
1.4% |
|
length of skid |
n/a |
32.34' |
n/a |
n/a |
You could then state that your measurement of the skid mark length was likely within 2.0% of its actual value. In other words, the length of the skid is likely within 0.6' of the value derived with PhotoModeler.