Messages

1

General / Export Multiple Regions from a Point Cloud in a Single Export

« on: March 02, 2024, 07:06:02 PM »

Hi All,
Is there a tool in Metashape Professional to export multiple regions from the dense point cloud in one export.  I have 30 study sites and a very high density point cloud and would prefer to only export the study sites to minimize the file size of the export.
Thanks,  James   

2

General / Re: Dense Point Cloud Gaps

« on: July 05, 2022, 07:19:47 PM »

Hi Alexey

I have definitely refined the sparse points a lot, trying to follow the steps and to get the recommended accuracies of a USGS methodology  (https://pubs.usgs.gov/of/2021/1039/ofr20211039.pdf).  The final accuracy in the Reference View is .009m, and .19pixels for the Chunk which is close to the recommendation.   I've attached an image with the processing steps and parameters.  For example, I filtered by Reconstruction Uncertainty 3 times, using 110 as the first threshold.  Projection Accuracy was used twice, and Reprojection Error was used three times.  The Chunks that were not used are stroked out in red. 

I had assumed that if the cameras were still calibrated at the end of the sparse point filtering, they would
be used for the dense cloud generation.  I can go back to one of the previous chunks during the sparse could filtering to generate the dense cloud, but the accuracies are not nearly as good until I get to the final filtering step and camera realignment.

There will be some movement in these images at the tree tops, but I was hoping the final sparse point cloud would be solid ground points. 

Thanks in advance for any suggestions.  I will look into upgrading the software. 
James 

3

General / Re: Aligning Aerial Photos of Forest Canopy

« on: October 28, 2019, 03:10:19 AM »

Thanks stihl for the suggestion.  I've tried different accuracy parameters, downsampled the images, and played with all the other parameters, but I'm not getting better results.  There must not be enough tie-points to align the photos and the only thing I can think of is increasing the overlap next time.   

4

General / Aligning Aerial Photos of Forest Canopy

« on: October 22, 2019, 11:20:37 PM »

Hi.  I'm trying to align approximately 800 aerial photos with 75+ side and forward overlap for a forested property.  The majority of the photos align but two large areas will not, regardless of the parameters used.  It is not clear from the spacing of the photos or the composition of the forest why the number of tie-points should be any different than elsewhere on the ortho.  The source of the imagery is a DJI Phantom, geotagged photos taken at 75m. 

The processing parameters used for the full dataset are: 
-high accuracy
-reference preselection
-120,000 key point limit
-0 tie point limit
-adaptive camera model fitting

I've tried pulling out the unaligned photos into a separate chunk and adjusting the parameters.  I've also added additional photos from another flight taken one week earlier, albeit with quite different lighting and leaf conditions.   Nothing has been able to align more than a fraction of these remaining images. 

Any suggestions or ideas would be greatly appreciated.   Currently, these areas appear distorted in the final orthophoto because the underlying DEM is filling gaps in the point clouds.   

Thanks,
James