Show Posts

This section allows you to view all posts made by this member. Note that you can only see posts made in areas you currently have access to.

Topics - wgreenePIMS

Pages: [1]
Bug Reports / Crashing on Mac eGPU
« on: May 24, 2023, 03:27:13 PM »
Hi there,

I'm running medium-size underwater coral reef datasets (~1500 24mp images) with the latest 2.0.1 Metashape Pro version on a Mac Mini (2018, 6-core Intel i7, 32GB RAM) with the latest operating system installed (Ventura 13.4) and a Sonnet Breakaway Puck eGPU with an AMD RX5700 8gb card. The setup works very well at accelerating most apps, but I've found that having the GPU checked in Metashape settings (so, actually making use of the eGPU) results in very frequent crashes, especially while executing GPU-intensive tasks like building depth maps and depth map-based meshing. My processing logs indicate nothing - there's no error noted in it, the program simply crashes. Does anybody have any suggestions for me? I know this is an unconventional setup to be working with, but I see no reason why it shouldn't work as it's supposed to. When it does work properly, it's remarkably fast and effective, but given the crashes (happening with almost every dataset larger than 1,000 photos), it's been very frustrating. Thanks in advance for the help!

General / Median orthomosaic blending option
« on: March 21, 2023, 07:38:15 PM »
Hi Alexey,

I have a question related to orthomosaic blending. In the vast majority of cases, using mosaic or average is suitable, but there are certain situations that I run into frequently doing multispectral drone surveys of coral reefs where there are very significant outlier images, where waves or sunglint completely blows out some pixel values. The average blending mode works well to iron out some of these issues, but in certain locations where there are more frequent issues (crashing waves on a shallow patch of reef, for example), average leads to unusable results, even though there clearly are plenty of images in the area that provide excellent source data for those pixels. Attached is an example of the problems introduced by average blending in crashing wave areas.

I think a median blending or a weighted average mode would work far better in some cases, so that outlier values do not affect the results. Is there any way to do this via python scripting or is there potential to include an additional blending mode in the orthomosaicking step? A median blending mode would seem to be just as computationally easy as average. I know it is currently possible to export orthophotos and blend them in other GIS software using more complex blending options, but this workaround is tedious and very time consuming.

I've also found that the traditional method of drawing a polygon and assigning images on the ortho itself does not work while using average blending - you are allowed to make multi-selections as usual, but when updating the orthomosaic, nothing changes. If this could be fixed, it would at least help solve the problem significantly by being able to manually exclude some images from the average blending in specific areas.

As always, thanks for the excellent help with all of our questions!

Bug Reports / Historic Aerial Alignment
« on: November 17, 2021, 07:57:42 PM »
I'm having an interesting issue with the alignment of historic aerial imagery in Metashape 1.7.3. I have a set of 69 scanned photos for which I have the focal length and film size/scan resolution. Most of the scans include all the fiducial marks, but some of them have one of the marks (on the top) cropped just out of frame. They are all sized the same in terms of pixel dimensions, so Metashape automatically recognizes them as a single calibration group. If I do not check the box for film camera with fiducials, Metashape is able to align all the photos without any issue, as there is plenty of overlap to work with. This method introduces some significant errors, however, because while the scans are the same dimensions, they're not all aligned perfectly to the fiducials, and thus the camera calibration is not super accurate. When I try checking the box for film camera with fiducials, and then calibrating fiducials, it does a good job of predicting the location of the fiducials that aren't set manually, even if the 4th one appears out of frame. At that point in the process, it seems like Metashape is doing it's job well. When I try to run a camera alignment after doing all the fiducial work, it cannot successfully align the set. Sometimes I get up to 34 cameras aligned, and the program seems to do a good job with the calibration, but I am unable to get the rest of the set to align. I'm not sure how to proceed because the project requires a high degree of accuracy (~1m or so), so any help would be much welcome. I guess a part of the question is whether Metashape is able to deal with historic imagery where in some cases, one of the fiducials is out of frame. Thanks!


Feature Requests / Median Orthomosaic Blending Mode
« on: August 16, 2021, 04:49:16 PM »
In most cases, the currently existing average and mosaic blending modes for orthomosaic generation work well. There are, however, circumstances where using a median blending mode instead of average would be incredibly useful. The example I've come across is creating drone-based orthomosaic maps where the water surface is present - if there's surface reflection / glare, then the mosaic blending mode produces very noisy results, because some images have extreme glare while others do not. The average blending mode solves the reflection problem, but introduces other issues, such as ghosting of objects that have poorly defined geometry, especially defoliated trees / shrubs, and the influence of especially bright spots or lighting changes on some image areas. A third blending mode, which simply uses the median pixel value for a given location, should help to solve some of those issues.  Median blending should be very easy to implement - it's already possible to accomplish in a GIS program by mosaicking exported orthophotos. It would save lots of time and effort to simply include it as an alternative blending mode within Metashape, though! If people have ideas about using Python scripting to accomplish this, that would work too  :).

Feature Requests / Underwater Photogrammetry: Mask by Depth
« on: July 20, 2020, 06:13:04 PM »
When using Metashape with underwater datasets, dense cloud noise is sometimes generated from source imagery from more distant photos. Water clarity can be a real issue with underwater photogrammetry, and a simple solution to the problem would be enabling a way to generate masks from depth maps. If after setting scale, you could set a distance threshold (say 4 meters), and areas where depth maps indicate that the camera is more than 4m from the surface to be reconstructed would be masked out. It seems like this wouldn't be too hard to implement and would enable significant improvements in underwater model clarity.

Pages: [1]