Problems with orthophoto of buildings

[nadar]

I'm trying to produce a clean orthophoto of a build-up area:

about 50% of the area is covered with residential houses and industrial hangars.
Photos were aquired in vertical view from a drone flying 75 m. ground resolution is about 1.5 cm
(sorry for double posting: I first added this requets for help in an existing topic, but did not get any answer...)

I generate a high quality densecloud. It looks fine (not too noisy).
If I generate the ortho using the mesh generetaed from the whole cloud, a got jagged roof borders, etc.
If I generate a mesh from a cloud filtered to keep only ground points, I got large triangles in the buliding areas, and this creates discontinuities in the roofs.

I'm now trying to export the classified cloud to Global Mapper, select ground points and calculate a raster DEM from these points. Seems OK
Then I generate a TIN model and I export it as DXF.
When I Import this DXF into Photoscan (using tools / import mesh), the TIN imports OK, but seems upside down:
when the model is view from the top, the mesh is displayed in dark grey.
If I rotate the whole model 180°, then the mesh is correct (various hues of blue), but applying textures doesn't work.
Does anybody have a suggestion to either flip the DXF model before importing, or rotate the mesh inside Photoscan ?

More generally: how do you deal with this type of images ?
Thanks

[Alexey Pasumansky]

Hello nadar,

If you create a mesh in PhotoScan, export it as DXF and then import back the same model - is it properly oriented in the model space?

[Alexey Pasumansky]

Hello nadar,

It seems that there's an issue with model import from DXF format (inverted normals). So I suggest to run the following script to invert them back:

Code: [Select]

import PhotoScan
chunk = PhotoScan.app.document.chunk
faces = chunk.model.faces
for face in faces:
    face.vertices = (face.vertices[0], face.vertices[2], face.vertices[1])

[Alexey Pasumansky]

Hello nadar,

Could you please check the DXF export from the latest version (1.1.4), whether there are no more problems with the inverted normals?