Photogrammetry versus Tachymetry |
| Photogrammetry | Tachymetry |
|---|
| Survey time for complete geometry: 2-4 hours. | Survey time for complete geometry: 7-10 hours. |
| Survey time for a few additional points: 2-3 hours (unless visible on existing pictures, then approximately 15 minutes). | Survey time for a few additional points: 1 hour (requires existing geometry). |
| Any visible point in the pictures can be measured afterwards (so at our office). | For additional points a re-survey is necessary. |
Accuracies:
Minimum
X/Y 1:10,000
Z 1:20,000
Main points
X/Y 1:20,000
Z 1:40,000
(no lower limit) | Accuracies:
Minimum
X/Y 1:10,000
Z 1:15,000
Main points
X/Y 1:20,000
Z 1:30,000
(lower limit: 0.002m)
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| Can be done with moving (floating) and deforming objects. | Can only be done with moving objects when there is enough space on board for the total station. Deforming objects cannot be measured. |
| Needs enough space around the objects (approximately 85% of the object's length next to the object). | No limitation to space. |
| What You See Is What You Get (WYSIWYG): the measured points are visible on the pictures. | No WYSIWYG, afterwards there is no 100% guaranteed check on what has been measured. |
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