Topics

1

General / Not all shapes visible on photos

« on: August 17, 2021, 09:37:14 PM »

I've imported a variety of shapes into my Metashape project. I can see all the shapes layered over the orthomosaic, but only select layers layered over a photo that spans the same area. Does anyone know why this is or how I can get all shapes visible on photos?

My workaround for the time being is to draw the same shape on top of itself on the orthomosaic, and then it's visible in the photos.

2

General / Measure 3D height from 2D image

« on: May 05, 2021, 06:14:48 PM »

Hello,

I'm trying to measure char height on trees from aerial imagery. I'm using the ruler tool in Metashape. I'm wondering if you have recommendations for other tools in Metashape that would allow me to measure char height more accurately.

My plan without a better tool is to measure char height in the images and then get some validaiton measurements in the field to create at least a correlative structure of char height across our site. However, I figure many brilliant minds before me have needed this, so there might be a tool out there that I'm missing.

I've considered and dismissed measuring char height in the dense point cloud. The flight overlap was low enough that the 3D reconstruction of many trees is poor.

Thank you,
Anna

3

General / how to see point shape colors

« on: April 01, 2021, 07:06:00 PM »

Hello,

When you create a shape layer, you specify a color for that layer category. Despite creating a few layers with specified colors, I can't view those colors when I create a point shape with any of those layers. The flags marking the point shapes are green when they're created in an image, and then they're blue or white on other images. I haven't figured out what a blue or white point shape flag means. For example, in the attached image there are two point shapes, one with a layer I specified as black, and the other assigned to a layer I specified as a darker green - however, I don't see these colors.

How can I view the layer color for a given point shape? Or do layer colors have a different use other than to view the point shape flag?

Thank you,
Anna

4

General / add metadata to markers

« on: March 16, 2021, 09:24:27 PM »

Hello,

I have marked tree locations in my metashape project. I'd like to add metadata to each marker (e.g., presence of tree regrowth - Y/N). Is there a feature to add metadata to markers? If not, I can submit this as a feature request.

As a work-around, I see I can add markers to groups. I could create groups for different metadata categories. However, after moving a marker to Group 1 or Group 2, I'm unable to see a list of markers listed in each group. Is there a way I can see which markers are assigned to different groups? Further, is there a way to rename groups?

Thank you,
Anna

5

General / Best practices for merging imagery from distinct spatial AOIs

« on: October 19, 2020, 08:31:40 PM »

Hello,

I have imagery from three missions, each covering an area close to one-another. Two of the areas overlap a little . How would you recommend I process these? Should I load each mission's imagery into a separate chuck on the same project and then merge them? If so, at what point in processing do I merge the chunks? I'm sure there are best practices for this case described somewhere, but nothing turned up in my searches, so thanks to anyone who can find a related post.

Cheers,
Anna

6

General / Convert CRS of cameras

« on: July 07, 2020, 11:51:57 PM »

Hello,

I have DJI P4P photos in WGS84 (EPSG::4326).

My markers are in NAD83 + NAVD88 + Geoid18. I can't find an undulation grid to import the markers directly into Agisoft, so I need to convert them beforehand. Geoid18 is a relatively new geoid model and thus not many conversion tools support it. The only conversion tool I can find for converting from Geoid18 is the NOAA Vertical Datum Transformation too. However, this only converts to versions of WGS 84, like WGS 84 (G1150) or WGS 84 (G1674). https://vdatum.noaa.gov/vdatumweb/

If I convert the markers to WGS 84 (G1674) and try to bring them into a sparse point cloud set as WGS 84 (EPSG:4326), then I get an error: Unsupported datum transformation.

1) What do you recommend I do? Do you have a recommendation for another coordinate conversion tool?
2) If I change the CRS for the cameras to the converted CRS of the markers before aligning the cameras and importing the markers, I can do this, but the lang/lat/altitude of the cameras don't change as converted coordinates should. How do I correctly change the CRS of the cameras?

Best regards,
Anna

7

General / What GCP accuracy to use for best quantification of uncertainty?

« on: July 07, 2020, 08:11:30 PM »

Hello,

In this forest surveying project, we're interested in having the best relative spatial accuracy possible. We collected GCP coordinates using a Trimble RTK system that gives vertical/horizontal accuracy for each coordinate. I'm interested in your opinion between two processing scenarios:

1) GCPs as truth. Use the default 0.005m accuracy for GCPs/markers, thus treating the GCPs as close to 'truth' as possible. Then for any analyses we do on the dense cloud, we can use the Trimble accuracies as the spatial error.

2) Use measured accuracy in processing. Use the Trimble-provided accuracy as the accuracy in Agisoft. Then for any analyses we do on the dense cloud, we use the MetaShape errors as the spatial error. However, in this scenario, I'm unsure how the Trimble accuracy and Agisoft error would interact for a given GCP coordinate.

I'm curious which of these two workflows you'd recommend.

Thank you,
Anna

8

General / What is the CRS of my cameras?

« on: June 25, 2020, 06:44:44 AM »

Hello,

I'm trying to reconcile a large vertical distance between my aligned point cloud and my measured GCPs, before manually georeferencing the photos with GCP coordinates - illustrated in attached screenshot

My workflow follows post https://www.agisoft.com/forum/index.php?topic=7851.0
1) Import DJI Phantom 4 photos
2) Manually remove images that are obvious 'outliers'
3) Estimate image quality and remove poor quality photos (my lowest is 0.8, so I remove none)
4) I skip creating a mask. Align photos (quality HIGH, pair preselection: REFERENCE, key point limit: 40,000, tie point limit: 4,000, adaptive camare model fitting: YES)
5) Import GCPs as markers

The difference in altitude between a GCP and a camera taken of that GCP ranges between 170-180m. This makes me think there's a mismatch between the CRS of the photos and the markers, but I'm not sure how to check this.

I know my GCPs are in WGS84. I am told that DJI Phantom 4 photos are also in WGS84, though I have been unable to verify this online. Are my assumptions of CRS wrong, or are the CRS different, or is there just a ton of error in the cameras?

The GCP coordinates were taken with a high-precision RTK GNSS device. We have elevation and ellipsoid height for GCPs, and are using elevation since that's higher than ellipsoid height. GCP coordinates attached.

Thank you for your thought and time in helping me clarify where my sources of error are.

9

General / meaning of XYZ error and est from exported markers

« on: June 04, 2020, 02:34:34 AM »

Hello,

I'm doing an analysis where understanding spatial precision in the point cloud is important. Specifically, we put out light sensors in a forest and took the exact GNSS position. I used these GNSS positions as markers in MetaShape to georeference the point cloud.

I've just exported the marker coordinates and I see that the columns Label, X/Long, Y/Lat, Z/lat, Accyracy_X/Y_(m), and Accuracy_Z_(m) are just as I specified upon uploading these coordinates. However, now I see 6 new columns: XYZ error and est. Could you please describe what the error and estimate columns mean?

Secondly, I've exported the forest point cloud and would like to plot these markers in the point cloud. Should I use the X_est, Y_est, and Z_est coordinates?

Lastly, but relatedly, if markers are meant to groundtruth the aligned photos in space, why is it that the markers get pushed and pulled such that new X_est, Y_est, and Z_est fields are created?

Attached, you'll find my markers exported from Agisoft Metashape as a txt (then converted to csv).

Thank you for your explanation. I look forward to hearing back!

10

General / Automatically save Metashape console logs?

« on: December 04, 2019, 05:05:09 PM »

Is there a way to automatically save the console logs for a .psx file?

For a typical project, I push processing along over several days. Every time I exit out of a psx file, the processing log from the console clears. It would be nice to have the console log saved automatically in some txt file, perhaps in the .psx files folder. Does this functionality exist?

I'm specifically interested in retroactively retrieving timestamps of processing steps.

11

General / Altitude or height (continued)

« on: November 19, 2019, 02:52:19 AM »

My question is a continuation from the old thread, "altitude or height": https://www.agisoft.com/forum/index.php?topic=4986.msg38769#msg38769

I used a Phantom 4 for forest surveying and am getting a large difference between my GCP and sparse point cloud elevations. Both the GCP and camera elevations are in AMSL (m). The UAV flew 116m AGL, and all camera elevations are between 3300 and 3400m. We used a Trimble RTK system with less than 1m precision to geolocate the GCPs, and these points' elevations are between 3140 and 3170m.

When I go to start manually georeferencing the images (i.e. Filter photos by marker and manually drag the marker to the visible GCP in image. Repeat 6 times or so), and then I click "Update", I see that the marker is pulled up to the sparse point cloud rather than the sparse point cloud being pulled down to the more accurate RTK coordinates. Why is this?

In the original "altitude or height" forum post, SAV responded to a similar question, advising to: "3. Uncheck all images/cameras in the reference pane so Photoscan will ignore their locations during Photo alignment and only use GCPs."

I imagine this answer could address my problem. However, I'm not sure what selections to make when aligning the photos. Here is my workflow to make my question more clear:
1) Upload photos
2) Remove images that are obvious outliers. (e.g. Estimate photo quality and get rid of ones below 0.7)
3) (I'm generating no masks, but would do that step here if I were)
4) Upload GCP marker coordinates with accuracy
5) Uncheck all images in Reference pane
6) Make sure images and markers are on same coordinate system.
7) Align photos (quality HIGH, pair preselection ??, key point limit: 40,000, tie point limit: 4,000, adaptive camare model fitting: YES)

What should my pair preselection be to create the sparse point cloud at the elevation of the markers and not of the cameras? Reference seems to be the best answer, based on the user manual. Why does un-checking the images in the reference pane affect how images align?