I have areas of dense vegetation in a large scale project, that makes it very difficult to set tie points.
Is there a way or method to patch or ‘fix’ the areas that Pix4Dmatic is struggling with?
Hi,
I am not a PIX4Dmatic expert, but the reason could be that those parts have higher altitude.
This causes the overlap to decrease (as objects are closer to the camera) so it will be difficult to reconstruct.
Try processing the complete project with Half Image scale.
Best,
Tried all different scales and they come up with worse camera calibration results.
The flight was flown with terrain awareness, so keeping a constant height above grown level across the hillside.
My theory is that the imagery Pix4dmatic is processing is all so similar, there are no uniquely identifiable features. Mainly treetops without any land, rocks, tracks etc. This approach worked fine across the areas that had been felled, but across the forestry areas, it is struggling.
I’ve read that covering the area with a higher altitude flight would help with the dense vegetation area. Pix4dmatic can apparently handle different altitudes within one project. I’ll give this a shot, but any other suggestions or pointers are welcome 
Hi @media1 ,
Just wondering was the result also not looking so well in 1/4 (Quarter image size, Fast)? Was reading this article Densify - PIX4Dmatic. It stated that quarter size images are used to compute additional 3D points. Less points are computed than with the 1/2 image scale and the processing time is reduced. This option can generate more points when processing vegetation areas.
An additional tip for dense vegetation area would be
- Increase the overlap between the images to at least 85% frontal overlap and 70% side overlap.
As you already mentioned indeed increase the flight height would help.
- Increase the flight altitude: When flying higher, the images suffer less from perspective distortions and it is easier to detect visual similarities between overlapping images in vegetation areas.
More info: How to improve the outputs of dense vegetation areas using PIX4Dmapper?
Sincerely,
Rosana