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Topics - radar_boy

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General / Using Leica DMC III images
« on: August 02, 2021, 06:23:26 PM »
I would like to use some stereo, vertical Leica DMC I and DMC III aerial imagery, provided as RGB in TIFF format. I have exterior orientation metadata as text, together with some interior orientation metadata (e.g. calibrated focal length, pixel size etc). I can import said data and metadata.

I have started by working with a block of >70 DMC III images and Align Photos to create a sparse cloud.

Unless I deliberately fix the focal length it ends up changing dramatically (>34000 mm vs. the calibrated 92mm). When I then use Model > Gradual Selection and progressively select points in the sparse cloud according to Reconstruction Uncertainty I get distinct structures forming:

When I fix the focal length the sparse point cloud appears thus:

These structures suggest systematic errors. I sense there is something wrong with the camera model? Is there something extra I should be doing to import Leica DMC images? Might the systematic errors be related to the fact DMC use multiple 2D arrays?

Camera Calibration / Clarification regarding Calibrate Fiducials
« on: March 20, 2020, 01:08:12 AM »
Am I correct in guessing that Calibrate Fiducials assumes the fiducial marks are symmetrical (equidistant from the principle point) and uses the given scan resolution to calculate their approximate coordinates? Is this done on a per-image basis, or use means (or some other statistic) if multiple images are selected together (therefore more representative coordinates)? I'm just seeking some clarification please.  ;)

If this is correct it'd be great to add such to the manual for future reference.

Many thanks


Feature Requests / Calibrate Fiducials: um & dpi options
« on: March 20, 2020, 12:56:23 AM »
When using Calibrate Fiducials it would be wonderful to have the options to input the scan resolution in um (microns) and dpi please.

Many thanks


There may be a way of doing this which I haven't yet discovered (please provide instructions if there is) but we really need a means creating 2D (i.e. horizontal) markers... i.e where only x,y coordinates were able to be measured. Also, where 3D markers are used (i.e. the only kind of marker I'm aware of in the current version) it would be very useful indeed to differentiate between 2D/horizontal (x,y) and 1D/vertical (z) marker accuracy, as the two are often very different indeed (e.g. when using GNSS to survey marker locations). Using just one overall Accuracy for each marker is very limiting when it comes to bundle adjustment with markers surveyed by different means or in different conditions.

The *.geom and *.vrt formats are becoming ever more popular for photo station ephemeris, camera models and RPC, not least in the airphoto sector. With 1000s of images having to be processed it is impractical to add this data manually. Can PhotoScan be updated to automatically recognise and import this data please?

Many thanks


General / Using *.geom for ephemeris and camera model for images?
« on: November 08, 2017, 01:25:08 PM »
I have a bunch of vertical and oblique airphotos I wish to use in SfM (*.jpg as it happens). Each one has a *.geom file, which appears to contain the photo station ephemeris data and the camera model for each. My question is, how can I automatically add all this metadata into PhotoScan. I have 1000s of images and doing it manually is not practical!

Many thanks in advance.


General / Using *.vrt for ephemeris/RPC of oblique airphotos?
« on: October 27, 2017, 07:37:17 PM »
I'm using oblique airphotos acquired by NOAA and made freely available as TIFF here:

Each TIFF comes with an associated *.vrt file... a format I'm not familiar with. To me it appears to contain ephemeris/RPC.

I want to generate geo-referenced point clouds, as well orthophotos from multiple TIFFs. Is there a way for importing the information from the VRT files into PhotoScan for this purpose (therefore with no GCP required)?

General / Copying markers between chunks
« on: April 29, 2017, 07:25:43 PM »
My project needs to be processed as several chunks. In the first chunk I have spent a lot of time carefully placing and naming a LOT of markers (non-georeferences, i.e. no XYZ coordinate, I just want to use them to align my chunks). How can I copy markers from one chunk and use them in another (granted, I'll have to place them all again in the photos, which is the whole point, but I won't have to carefully name each one over and over for each of my multiple chunks)...???

General / Patches of high/low areas in point cloud of terrain
« on: December 20, 2016, 06:31:22 PM »
I'm using some vertical aerial photographs to create a Digital Elevation Model (DEM) and orthophoto of the terrain. I have ground control points (GCP) measured using Differential GNSS. The images align very well and the production of the dense point cloud (setting High) goes according to plan. However, in the point cloud there are gaps, where patches of ground are noticeably higher or lower than that surrounding it. It is hard to see without panning around, but when creating a mesh from these points the patches and their edges become really evident. This is nothing like the actual landscape. How are these caused and how can they be corrected?

Many thanks

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