Topics

1

Camera Calibration / PPK for the Multispectral bands on the DJI Mavic 3M

« on: July 24, 2024, 01:30:51 AM »

Hi,

I recently got a Mavic 3M, and use PPK with a non-DJI GNSS base station for the RGB camera which works normally as expected.

I then had the idea of applying the PPK to the multispectral bands by creating a simple python script that took the PPK csv file from the RGB images, copied the coordinates and accuracy, and applied to each of the 4 multispectral bands. So now instead of having the csv with 1 row per camera, I have 4 (1 for each band).

I would have assumed if I "Import Reference Data from File" it would have seen the name of each band and apply the PPK information... but it doesnt seem to be recognizing it
Is there something I have to do differently when using a multi-camera system?

Cheers

2

General / Point cloud is not lining up vertically with GCPs

« on: March 20, 2024, 12:32:47 AM »

Hi!

I am having trouble understanding why my model is not aligning vertically with the GCPs...

For context, I flew 2 flights a few months apart to monitor erosion on a plateau and slope with a study area of ~250m x 150m. I placed 12 GCPs and recorded their locations using a Stonex GNSS rover/base station. I then followed the methodology for Best Quality Workflow as outlined in this paper (https://www.mdpi.com/2072-4292/14/6/1312, other than only assigning 6 images to each GCP instead of every single image, as there are over 1000 images in my model. I also unselected 2 GCPs to use as control points.

My question is why is the point cloud 6cm above the GCP elevation in the bottom right corner and 4cm below the GCP elevation in the top left corner (see screeshot), given that the processing report (see attachments) shows the Z error much lower???

any help is much appreciated!!!

3

Python and Java API / Split in chunks script selecting point confidence

« on: January 12, 2024, 09:34:21 PM »

Hi!

I use the split in chunks script to help deal with the size of some of my models and I was wondering if there is a way to include point confidence in the script? The option is available when building a dense cloud normally (https://agisoft.freshdesk.com/support/solutions/articles/31000162209-point-cloud-editing-with-confidence-filter-tool) but after running the script on a chunk the point cloud didn't include point confidence. It may be a default I need to change??

Cheers

4

General / Dense cloud point confidence filter standard

« on: January 09, 2024, 09:55:42 PM »

Hi!

I see that you can filter the dense cloud by confidence, and remove low confidence points. I was curious if there is a standard threshold to use, or if its dependent on each model? For example, using a threshold of 0-10 seemed to remove all the noisy points while minimizing creating holes in the dense cloud. What threshold does everyone else use?

5

General / Dense cloud artifact

« on: January 09, 2024, 02:41:08 AM »

Hey, I have been having issues with artifacts showing up in my dense cloud models for erosion modelling. It appears to be an alignment issue, but I am not sure which parameters I need to change in order to fix it?? I currently use highest setting to align the cameras, remove all cameras with quality <0.7, add the GCPs and create dense cloud on ultra high with mild depth filtering. Below is a screenshot of one of the artifacts as well as part of the processing report with the parameters used.

Any help is greatly appreciated
Cheers!

6

General / tie point visualization appears pixelated

« on: June 30, 2022, 01:24:05 AM »

Hi,

I've been scratching my head trying to figure out this visualization issue I'm having. When I open a project on my laptop, the sparse and dense clouds appear normal, with the points represented as very small dots/squares, however when I open the exact same project on my desktop, the points are enlarged and appear like large pixels. This throws off the visualization of the model, but doesn't seem to affect building the DEM and ortho. Is there a setting somewhere that indicates the size of the tie points (ie. similar to choosing point size for symbology in ArcMap or QGIS)? I attached a screenshot with the two sparse cloud models side by side to show what I mean

Cheers!

7

General / placement of GCPs partially covered at edge of images

« on: February 10, 2021, 08:01:08 PM »

I am building dense clouds from UAV images, and in my workflow I used frisbee discs as GCP markers. In some of the images, the frisbee is partially covered by shrubs/tree trunk (at the edges of images) but I can still see a piece of the frisbee, although not the center of the frisbee...
My question is if I place a marker on that frisbee, will the marker adhere to where the actual frisbee is, or will it put the marker on the first point it reaches? ex) the top of the shrub that is partially blocking the view of the frisbee. I am thinking that if the marker adheres to the first point (top of the shrub), the coordinates would be slightly off in my model, and thus I would want to not include the marker on those images that have these affected points?

Any feedback or suggestions are appreciated!