Measurement Accuracy

[ankur6ue]

Hello:

I used Photoscan to make a model of a house from Aerial pics. The model looks great, however the measurements obtained are different from the physical measurements by a scale factor that is not very consistent. This is making it hard to get good physical measurements from the model.

A screenshot of the model in Maya is attached.

I used a GoPro 4 attached to an Iris drone to collect the pictures. I wanted to capture as much detail as possible, so I flew the drone close to the house. The camera was 2-8 m away from the house in most of the pictures

Tried the measurements in various point cloud viewers as well as using Photoscan markers. Results are broadly consistent. Any ideas as to what can be done to obtain better measurement accuracy?

[ArtursJu]

Nice pic. I hope I will do some tests with building model next week. Did you measured some control points on house for more accurate modeling.

[Santiago]

Hi ankur6ue,

Have you tried using markers that you know exactly how much they measure. I tried it once for a 3d modellin of a vehicle and the accuracy was very good. You could try measuring a corner of the house, where you would give that corner a starting point of 0, 0, 0 in XYZ or lat, long, alt. Then you could create 3 end points and in markers input the distance between the corner and those 3 end points.  Having done that everything would be scaled based on those know points. You could do this for several parts of the house which you know exactly how much they measure (by using a measuring tape).

I think this should work. Sorry if it isn't clear enough.

Best regards,

Santiago

[frank.stremke]

Hello
to understand your question better:
how did you scale your model in the first place?
frank