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1
General / DEMs From Scanned Historical Aerial Images
« Last post by RoryScott on Today at 02:49:38 PM »
Hi everyone.

I’ve been attempting to produce a good DEM (RSME <1m) from a series of historic aerial photos, originally captured on film in the year 2000. The images are captured in single flight line with approximately 40% overlap. I unfortunately don’t have the camera calibration certificate, however it is known that the camera model was an “RMK TOP 15” system with a focal length of 153mm.

I’ve been using a series of GCPs (derived from a LiDAR reference DTM) for ground referencing and have had mixed success in generating a DEM.
Using the known focal length and image-space coordinates of the fiducial marks (fiducials auto marked and verified) I attempted to process using the “film camera with fiducials” option checked in camera calibration. This does produce a tie-point cloud, however dense cloud generation fails, citing error “Zero resolution”.

Processing without “film camera with fiducials” checked produces a more dense tie point cloud, however the final dense cloud and DEM have much vertical error.
Metashape appears to capture the terrain form, but in places the produced DEM is vertically separated by several meters from the reference LiDAR DTM. This error is variable across the model. Adding extra control points to error areas seems to have no effect.
 
 
The best workflow I have is as follows (not using fiducial marks):

-Import scanned images
-Manually place un-georeferenced control points to aid camera alignment step.
-Align cameras
-Place and import reference data for GCPs (acquired from LiDAR at road junctions, football pitches etc.)
-Optimise alignment with markers checked
-Build dense cloud, DEM

Is there anything I can to get my model to better align with the reference DTM? Any experiences or suggestions would be really helpful. Please let me know if more detail is needed.

Cheers.
2
General / Why does the blue flag in the Ortho Tab moved ?
« Last post by PROBERT1968 on April 04, 2020, 03:18:13 AM »
Deleted ...duplicate !
3
Python Scripting / Apply transformation matrix to a chunk
« Last post by jnb on April 03, 2020, 10:17:10 PM »
Hello,

I'm trying to apply a transformation matrix to a chunk in python, but I am struggling. 
My workflow for now :

- export a scaled model (local coordinates)
- open it in another software to give it correct orientation
- grab the corresponding matrix and apply it in Metashape

Exemple : 

Code: [Select]
import Metashape

doc = Metashape.app.document
chunk = doc.chunk
S = Metashape.Matrix().Diag([1, 1, 1, 1])

T = Metashape.Matrix([[0.9997743489568586, -0.0211954660930352, -0.0014154098306438, -13.4365763350189269],
                      [0.0000000000000000, -0.0666304947728083, 0.9977777193174494, 851.1973959656927491],
                      [-0.0212426732755011, -0.9975525697342621, -0.0666154595321578, -1634.9351050186285192],
                      [0.0000000000000000, 0.0000000000000000, 0.0000000000000000, 1.0000000000000000 ]])

chunk.transform.matrix = S * T.inv()


The model is indeed moving, but not correctly. The scale is also wrong (I have to hit update in Reference pane to get it right). So what I am doing wrong here ?
Thank you for your help !

4
Python Scripting / Sentera 6X Camera Support
« Last post by Graytr on April 03, 2020, 07:50:29 PM »
Hello there,

I was wondering if there were any plans to support the Sentera 6X multispectral camera? (https://sentera.com/6x/)
The images from this camera are 5 band tif files (Blue, Green, Red, RedEdge, and NIR). There is also an EXE runnable that Sentera provides that can automatically split the image into 5 subfolders; one for each band.

I have attempted to run Metashape on both of these options, the straight tif files and the folder structure. For both "Import Photos" and "Import Folder" I selected the Multi-Camera System. Both options work as expected and import the images as 5 bands. Furthermore, the python function chunk.addPhotos(list_of_paths, Metashape.MultiplaneLayout) provided no difference from the GUI operations. From what I can tell, there may be no issue with the image import. The only problem I've noticed is that, when viewing an image, it shows all 5 channels side by side instead of just the master.

The problem is that the orthomosaic it produces only has one band - the master band specifically.

The drive link is a sample image as well as a sample of the same image split into the 5 bands (sorry but it was bigger than the 512KB limit). Can you perhaps help me figure out how to produce 5 band orthomosaics?
https://drive.google.com/file/d/1O26XpycRiPnLFhAU16P61uveiPfqWhJN/view?usp=sharing
5
Hello jmsuomal,

Sometime the information is duplicated in XMP and EXIF tags, we'll check, if it is possible to read the required information from XMP only, if the corresponding EXIF tags are missing.
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General / Re: Blue flag in Ortho tab looked like they have move !
« Last post by PROBERT1968 on April 03, 2020, 05:30:23 PM »

NEVER MIND !!!!

I figure it out yesterday ....  had to use remove projections to reset it.....  That means I have to re-do all over again and fix it... I could not what I need...

Is there a better way around to do this ?

Learn lesson  don't update transform too much it shifts a lot...

7
Feature Requests / Re: Need a tool to export a few select markers or shapefiles
« Last post by smiller on April 03, 2020, 10:59:50 AM »
This would be a great tool to add, simply some check boxes to select which shapes or markers to export. One way around this is to create folders for the markers. I also create shape groups and export those. But, sometimes it would be nice to also have that flexibility or which shapes to export rather than rearranging the folders/groups, and then exporting.
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Bug Reports / Re: TIFF import does not read the camera Make and Model EXIF tags
« Last post by jmsuomal on April 03, 2020, 10:18:07 AM »
Dear Alexey,

That solved it! I simply replaced in the exiftool command the "-XMP:TagName=" with "-TagName=" and it now works perfectly.

Peculiarly, the XMP tags worked perfectly well with the JPEGs and the even the TIFFs were able to load other fields such as GPS location and pixel size XMP fields.

Anyway, that solved it for me. Thank you.
9
General / Plan plotting out of metashape
« Last post by Origin Surveyors on April 03, 2020, 03:24:46 AM »
Hi everyone

I was wondering what the plotting capability is straight from Metashape.

Usually I export the data to a point cloud software and then to 12d and potentially AutoCAD, but have never considered plotting plans straight from Metashape.

Has anyone done this?

Would anyone care to share some links to some examples to show what can be done, as far a PDF / jpeg plans?

Looking for some inspiration.

Thanks

Brett
10
Python Scripting / Re: Gradual Selection Python Script
« Last post by rbnkc on April 03, 2020, 12:47:14 AM »
Thank you Alexey,

The gradual selection procedure I’ve found, that has been successful for my work is:
1.   Reconstruction Uncertainty – 50% of points or as near as possible to 10
2.   Optimize Cameras
3.   Projection Accuracy – 50% of points or as near as possible to 2.5
4.   Optimize Cameras
5.   Reprojection Error – 10% of points or as near as possible to .3
6.   Optimize Cameras with all lens parameters checked
7.   Repeat Reprojection Error/Optimize Camera until all above .3 pixels on reference error removed

The examples you provided I think contain all the elements needed for this. The target values and percentages can be constants. Some error checking on the iterative procedures would be probably be necessary. I may be able to put something together with this. It looks pretty straight forward. Any help would be greatly appreciated.
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