Agisoft Metashape
Agisoft Metashape => Bug Reports => Topic started by: Erik Holmlund on December 05, 2017, 07:04:22 PM
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Hi,
I'm very interested in the new fiducial support, as it greatly reduces the effort of using analog imagery. I can however not make it work completely, as marker placement seems non-functional.
If I use the images separately as non-analog, the marker placement works (as bad as it does without fiducials). If I specify the fiducials and place a marker, it ends up on the other side of the solar system. Below is an example of an estimated coordinate I get, from a point added through the sparse point cloud:
East 8 144 283.304 m
North: 13 169 867.186 m
Altitude: 7 982 093 517.095 m
The pixel error is also massive, at 2895.922.
My suspicion is that the internal coordinate system produced by fiducial placement is wrong, creating invalid marker projections and therefore the position. The fiducials I have in the same project are:
X,Y in millimeters, with the focal length: 152.83 mm
Upper left: -106.073, 105.904
Upper right: 105.919, 106.098
Lower right: 106.06, -105.902
Lower left: -105.906, -106.099
I've tried it in several projects, and with different X and Y directions (positive X or negative X etc.). I've also tried the calibrate fiducials tool with no change.
Reproducing the problem is as easy as importing the images, placing fiducials, calibrating them, aligning the images and then placing a marker in the point cloud.
I would love to have the tool working, but evidently it's clearly not!
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Hello eriksh,
Please check build 5432 of PhotoScan Pro 1.4.0 (available in the pre-release thread). There were fixes related to fiducial marks included.
However, I can suggest to start the project from scratch, if possible, in order to avoid possible mess of fiducials and markers from the previous version project.
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Hi Alexey,
I had completely missed the latest build! Now it works like a charm.
Thanks!
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Hello eriksh,
Ok. Let me know, if there are any other issues (or requests) related to the workflow with fiducial marks.
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Hello again,
I seem to have been a bit quick in saying it works perfectly, since I have quite the list of bugs.
- When exporting markers and reimporting them, the fiducials show up in the markers panel, with image coordinates as reference coords. If they're removed, the fiducials on the image are removed as well.
- If I add a new fiducial in an image, it doesn't show up in the camera calibration. The only way to then remove it is using the console (chunk.remove(chunk.markers[-1]).
- If I have a good (subpixel) alignment on the 'fiducial chunk' and specify the projections of three GCP's, they show up correctly in the point cloud, with reasonable pixel errors. I can then properly align two chunks with the same GCP's using Align Chunks (with markers). If I however give the GCP's reference information and update the transform, the errors shoot up to thousands of meters. The whole terrain is also vertical. I know that the GCP's have correct coordinates, since I can align them with Align Chunks to a chunk with digital imagery.
If I subsequently run Optimize Cameras (with marker reference data unchecked), the whole alignment goes haywire, with both marker and camera reprojection error ranging from 52-1483 pixels. If I run the optimization with reference checked, the errors are even higher at 1269-7553 pixels. - I also noticed something weird after using Align Chunks with markers on the fiducial chunk. If I look around in the model that I used to align, everything is normal. If I however switch to the fiducial chunk and rotate the camera, the whole model jumps so that everything is tilted by maybe 10 degrees. If I just move the camera, nothing happens.
The only thing I suspect I might do differently is to rotate the images in PhotoScan so they face north. Could that mess with the fiducials?
I'd love to help out with providing projects and such, if it might help.
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Hello eriksh,
Thanks again for reporting.
It seems that fiducials type is not properly read from the XML when you import back markers. Also currently fiducials were really used as markers in the marker-based chunk alignment, that caused the problems you were observing. We will fix these issues in the next 1.4.0 update. Also the problem with New Fiducial that is not added to the fiducials list.
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Nice to hear!
To clarify, marker-based chunk alignment works well. It's the chunk update and optimization that don't work for me.
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Hello eriksh,
Ok, I'll double check the reported problem with optimization/update.
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Hello eriksh,
The new update of 1.4.0 is out now (build 5532), so I can suggest to check it out when you have time for that.
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Hi,
I just updated to build 5532 and it seems to be working in the two instances I tested! I'll update on any issues if they arise. But for now, thank you for these great new features!
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Hi,
I'm struggling to use the fiducials for aerial photos calibration.
I could input the coordinate in the calibration menu, then locate them on the photos. But optimize don't give good result.
Probably it's not the good workflow.
Could you give a workflow on how to correctly use fiducials for an aerial picture project?
cheers,
jules
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Hi jooles,
Are you sure you're using the coordinate signs (plus/minus) in the right direction? I had issues to begin with, where I set y as positive when it was supposed to be negative there, and so on.
If you don't know which dimensions should be positive or negative, I'd suggest doing an automatic calibration of the fiducials' position when you've placed them correctly. The numbers will likely be wrong, depending on which pixel size you use, but then you can note where the positive/negative signs should be.
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Hi Erik,
thanks for the very quick answer,
I'm don't know how to do this automatic calibration using the fiducials. Is it an optimize in the reference panel? Is it a right click on the images in the calibration panel and a "calibrate fiducials"?
More generally, is there a documentation on this workflow?
Jules
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Hi,
It's the "Calibrate Fiducials" that I was talking about.
I would also love some documentation, as I'm only by experience convinced that I'm doing everything correctly!
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Hello,
Just as a side not regarding fiducials support, in the version 1.4.2 it is planned to release the feature of automatic fiducials detection (providing they have generally circle shape - the presence of crosshair elements do not matter).
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Hi Alexey,
That sounds like a really useful feature!
May I also suggest adding "gray fiducials" that appear in the approximate vicinity when more than two fiducials are placed in an image? This would definitely speed up the workflow, as right clicking and adding each fiducial through the menu is quite time consuming.
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Hello Erik,
Actually, not sure, if it is possible to predict the location of fiducials before any of them are placed (the scanned image may be rotated anyhow), but I assume that it should be possible to give some prediction (gray fiducials) after 3-4 fiducials are placed and the relative fiducial locations are defined in Camera Calibration window.
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Hi Alexey,
What I imagined was if either fiducial locations were specified or if all fiducials are placed in at least one image. With that, wouldn't just two fiducials be needed for an additional image for a (crude) estimation of the internal coordinate system, and thus make an approximate placement of the others possible to aid the user?
I often find myself working with 40-50 images, with 8 fiducials each, thus requiring hundreds of manual placements. I've seen other photogrammetric software where such a feature already exists, and having such a feature here would really speed it up!
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Hello Erik,
I think two marks would be insufficient, and three might be fine already for the rough estimation. We'll put it to the feature request list.
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Hello Erik,
Please check version 1.4.2 in the Downloads section, it has an automatic feature or suggesting fiducials (with gray arrows), after at least two fiducials are already placed on the image.
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Hello Alexey,
According to your previous posts, i'm not sure if i understood well... which kind of following fiducial marks can be deteced in the automatically way by PhotoScan? ony circles?
(https://image.ibb.co/giPx1p/asd.png)
I'm asking because few years ago i developed method to preprocessing archival photographs to suitable form allowing to use them in Structure from Motion technology. For this purpose, an automatic algorithm, implemented in the application called SAPC (Scanned Aerial Photographs Correction), which transforms scans to a form, which characteristic similar to the images captured by a digital camera, was invented. Images, which are created in the applied program as output data, are characterized by the same principal point position in each photo and the same resolution through cutting out the black photo frame. Additionally, SAPC generates a binary image file, which can mask areas of fiducial marks. I am pleasantly surprised that you have added a new feature in PhotoScan for archival photos. It looks promising!
Link to my paper about SAPC: https://www.researchgate.net/publication/317307995_SAPC_-_APPLICATION_FOR_ADAPTING_SCANNED_ANALOGUE_PHOTOGRAPHS_TO_USE_THEM_IN_STRUCTURE_FROM_MOTION_TECHNOLOGY (https://www.researchgate.net/publication/317307995_SAPC_-_APPLICATION_FOR_ADAPTING_SCANNED_ANALOGUE_PHOTOGRAPHS_TO_USE_THEM_IN_STRUCTURE_FROM_MOTION_TECHNOLOGY)