Messages

1

Python and Java API / Re: Console output and stdout

« on: June 14, 2021, 12:07:47 PM »

Thanks for the reply.
Yes, this is the way I am currently doing it, redirect everything to some file. But this gives me no flexibility. Since the metashape workflow is just part of a bigger processing chain (of which I also want a couple of lines of comprehensive output), I cannot selectively decide which part of the metashape output I want, and which I don't. The workaround I have now is redirect everything to some temporary file, and log the parts I want from metashape (x/x cameras aligned, ortho written etc) manually. I was just hoping there would be a more elegant way to deal with the metashape console output.

2

Python and Java API / Console output and stdout

« on: May 27, 2021, 09:53:14 AM »

Hi!
I am including metashape api (version 1.5) into a larger processing chain, and my goal is to tame the console output a bit, and only log essential values from the alignment/densecloud/orthomosaicing process. Unfortunately this does not work easily, since there is no variable to control the verbosity of the chunk..*() functions. Redirecting stdout (via contextlib or directly) does also not work for some inexplicable reason. Any idea how to deal with this?

3

General / Re: Dealing with Reference Height Inaccuracies while creating a DEM with a Phantom 4

« on: December 05, 2017, 01:11:46 PM »

I actually have a question of a different sort. I see that you are using a DJI Phantom 4; however, you do not mention what type of Flight Planning software that you are using. This can make a slight difference for the imagery that you collect because if you are not flying a perfectly flat plain, you may have differences in elevation due to the Flight Planning software package that you use.

I am actually using a custom script for this, which sets a constant flight altitude depending on my desired gsd.

Hello marg,

To uncheck all cameras in the Reference pane via Python it is necessary to perform the following:

Code: [Select]

import PhotoScan
chunk = PhotoScan.app.document.chunk
for camera in chunk.cameras:
    camera.reference.enabled = False


Gonna try this now, thanks! Could you maybe comment on how the camera accuracy setting works? Because it does not actually seem to constrain the camera location estimation to much?

If you want to still use the EXIF location information, then you'll have to fix it first. DJI's drones record the relative altitude above point of take-off, which means if you add the altitude of the point where you took off to the relative altitude values that are recorded in the EXIF information, then you can get the 'real flight altitude' which will probably be within within Potoscan's default camera accuracy value of 10m. This has do be done either using 3rd party software or by running a Python script.

Hm, getting the takeoff altitude might be tricky though...Since my mission consisted of 3 flights, I'd have to lookup these 3 locations and assign each image to one of them...Can't think of a reliable way to do this off the top of my head.

4

General / Re: Dealing with Reference Height Inaccuracies while creating a DEM with a Phantom 4

« on: December 04, 2017, 07:28:20 PM »

I tried something similar before by removing all exif location information with a python script, but had similar results (large altitude variance, hanging bias...) but I could try this. Do you know how the exif camera reference could be deactivated in python? Also, this means I can't use Reference Preselection, right? Which one am I supposed to use instead?
Thanks!

5

General / Re: Dealing with Reference Height Inaccuracies while creating a DEM with a Phantom 4

« on: November 29, 2017, 02:01:22 PM »

My workflow at the moment is a little bit convoluted, but I'll attach the (commented) script. Feel free to comment on my code.

6

General / Re: Dealing with Reference Height Inaccuracies while creating a DEM with a Phantom 4

« on: November 29, 2017, 11:50:45 AM »

In my image, the blue dots are optimized. As you can see, the variance in altitude is a little bit lower, but it is still quite high and there is this hanging effect. What do you mean by messing with the EXIF data? I tried using unaltered EXIF reference altitudes before. They are around 40-50 meters, which is either above ground or above home, I'm not sure. Still the exact same problem of very high altitude variance and systematic bias after alignment and optimization.

7

General / Re: Dealing with Reference Height Inaccuracies while creating a DEM with a Phantom 4

« on: November 28, 2017, 01:53:45 PM »

I have ground control points, measured with subcm accuracies. I know that the uav gps is far less accurate than 1 m, I’m just looking for ways to counter the large variability in estimated heights…

8

General / Dealing with Reference Height Inaccuracies while creating a DEM with a Phantom 4

« on: November 21, 2017, 11:44:27 AM »

Hi,
I am trying to align about 1500 Phantom 4 images of a wheat field, shot from about 37 meters above ground. The aligned camera heights show a rather large variance. The image example shows the reference information in green (from image exif), the aligned cameras in red and the optimized cameras in blue. Optimization seems to counteract the large spread in altitude, but it’s still quite bad. I tried to add some constraints to the estimated height with chunk.camera_location_accuracy. I set the camera accuracies to 1m but this does not seem to reduce the spread and the bias at all. Any ideas?

9

General / Re: Altitude Accuracy of Crop Mappings with Phantom 4

« on: April 20, 2017, 06:33:28 PM »

All the photos are from 3 consecutive flights from the same day. I tried so far two differerent altitude values as camera reference:
1: Altitude from EXIF, no idea which of the altitude values photoscan uses by default
2: Altitude values interpolated from the flightlog. I basically pulled the timestamps from EXIF and looked up the altitude of the drone in the healthydrones logfiles.
Neither approach worked particularly well.

The altitude from the healthydrones log is NN I think? Marker altitude is above geoid by default, but I converted it to nn as well. Do you think above geoid altitudes will make a difference?

10

General / Re: Altitude Accuracy of Crop Mappings with Phantom 4

« on: April 20, 2017, 04:06:12 PM »

I have the topcan reference coordinates in geographic coordinates (WGS84) as well.
Well, I'm not exactly sure what the rolling shutter option does, but I thought it would at least help with the "hanging" problem. I know it can't miraculously fix not having markers spread out evenly.

I have not set any camera angles, and I have not made any adjustments to the accuracies of markers (which apparently defaults to 5 mm) or cameras (which defaults to 10m). I think the marker accurace is probably to good, but the topcon accuracy is usually below 1 cm so its not that far off. I have no idea what the camera accuracy is like, but its probably a bit better than 10 m. In what way do these Accuracy estimates influence my results? And do you think it might help to adjust them a bit?

11

General / Altitude Accuracy of Crop Mappings with Phantom 4

« on: April 20, 2017, 03:05:53 PM »

Hi,
I am trying to map the height of a winter wheat field of around 14 hectares with a Phantom 4 (I already know due to the camera the vehicle is not perfectly suited for this, but it's the only one I have). I tried loading the roughly 1500 images into agisoft with python scripts, varying alignment quality and other things like the newly added rolling shutter compensation in the optimization process. Additionally I have 13 markers on the field, measured with topcon hiperv.
The problem is, these markers are all around the field, not inside.
The attached images show camera positions (green: reference from exif, red: position after alignment, blue: position after optimization) and marker positions (green: reference, red: estimate after optimization) as well as the correlation coefficients for latitude, longitude and altitude.

Now I have 2 basic problems, and hopefully someone more experienced than me can add something to this:
1: Latitude and Longitude don't change much after alignment, but altitude changes a lot.  The Variance Increases a lot, even though the UAV had a pretty stable height during the flight. Additionally, a "hanging" effect is clearly visible in the middle of the field. This makes sense since there is no reference data there, but I hoped the rolling shutter compensation would counter this effect. Sadly it did not help much, but in some cases the curvature is reversed. But generally altitude is still all over the place. Any Ideas how to tackle the issue?
2: In some cases correlation of reference and estimated altitudes is alright (like in this case here) but if I up the accuracy, the correlation gets way worse. For instance PS.Accuracy.MediumAccuracy looks good but PS.Accuracy.HighAccuracy results do not? I thought higher alignment accuracy has no downsides (aside from the increased runtime)?

Thanks for your time

12

General / adding non DMS location data to exif of images

« on: March 16, 2017, 04:53:45 PM »

Hi,
I am trying to process around 1500 DJI Phantom 4 images to produce a 3D Model, and as many others I am trying to deal with gps altitude errors and such. I have found a way to replace the altitude with something better (i think), but I would also like to replace the long and lat coordinates with values from my local coordinate system, which is in meters. Sadly this is not possible since  the GPSinfo tags are in this weird format with three fractions for degrees minutes and seconds. Is there a way to add geolocations to the exif info directly without importing camera geometry with csv files?
Thanks!

13

General / Re: Photoscan Peformance on Dell server without GPU

« on: September 29, 2015, 09:19:23 AM »

Ok, I'll try it then, thank you!

14

General / Re: Photoscan Peformance on Dell server without GPU

« on: September 26, 2015, 11:05:29 AM »

So does that mean that particular step (which is very important for me) will not work at all, or will it just be slower?

15

General / Photoscan Peformance on Dell server without GPU

« on: September 25, 2015, 11:25:04 AM »

Hi,
just wanted to know if anybody has got experience running photoscan for aligning and point cloud generation on a server with no GPU. The server is a Dell r520 with 2*6 core Xeons with HT. It also features 96 GB of RAM. It will be running Ubuntu. How will the performance of this system compare to a regular desktop machine with dedicated GPU (like an i7 GTX 980 combo with 16 GB RAM)
Any ideas?