16
General / Re: About error zero resolution
« on: November 29, 2016, 08:16:53 PM »
I changed the system from wgs84 to utm32n, maybe thats the reason
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17
General / Re: About error zero resolution
« on: November 29, 2016, 03:59:51 PM »
Hi Alexey,
thank you, now it works.
Dont know, when or how I misplaced the bounding box at the first time
thank you, now it works.
Dont know, when or how I misplaced the bounding box at the first time
18
General / Zero resolution
« on: November 29, 2016, 02:56:55 PM »
Hi,
I just finished an UAV-Flight.
I alligned 254 photos, accuracy "medium".
Everything seems to be ok.
When I try to build the dense cloud, an error window, which says
"Zero resolution"
appears.
My workflow is as usual, same as many (succesfull) times before.
What does "Zero resolution" mean in this case?
Any idea, what is my mistake ?
I just finished an UAV-Flight.
I alligned 254 photos, accuracy "medium".
Everything seems to be ok.
When I try to build the dense cloud, an error window, which says
"Zero resolution"
appears.
My workflow is as usual, same as many (succesfull) times before.
What does "Zero resolution" mean in this case?
Any idea, what is my mistake ?
19
General / Re: Pig4Dcapture, Phantom 4 and Agisoft Photoscan.
« on: November 29, 2016, 08:52:19 AM »
yes
20
General / Re: Photoscan exporting near spherical model
« on: November 24, 2016, 12:36:38 PM »
Hi,
did you use GCPs or just GPS-Data?
did you use GCPs or just GPS-Data?
22
General / Re: camera calibration
« on: November 03, 2016, 08:54:54 AM »
Hi Tom,
in the landscapes which you compared, have there been any high objects over ground like trees or buildings?
I guess, that in such cases auto-focus could bring a wrong result.
I am not a fotografer, so maybe I am wrong. But I thought, if taking fotos from up to 50 m and more, the focus should be on "infinite" distance. If there are no high objects over ground, why does it make a difference wether the focus is set fixed manualy or set by the camera in automatic mode ?
Frank
in the landscapes which you compared, have there been any high objects over ground like trees or buildings?
I guess, that in such cases auto-focus could bring a wrong result.
I am not a fotografer, so maybe I am wrong. But I thought, if taking fotos from up to 50 m and more, the focus should be on "infinite" distance. If there are no high objects over ground, why does it make a difference wether the focus is set fixed manualy or set by the camera in automatic mode ?
Frank
23
General / Re: camera calibration
« on: November 02, 2016, 08:51:17 AM »That pattern is typical of a camera that was set to autofocus. Unfortunately, I have seen it many times.
It also answers your question in another post about Z accuracy. If the camera has been autofocused, the camera calibration will never be as good as it should be. The resulting error manifests it in Z and is typically 10 to 30 times more that it would be if the images were captured at a fixed focus and the camera calibration is fully optimized.
You can still make decent orthos from such projects, but volumes and elevations will unpredictable and should not be depended on.
Tom
I think, for low-distance-fotos (sculptures, buildings etc) this is very correct.
But I wonder, if it also is important for UAV-Modells.
The ground disatance usually is more then 50 m or so.
Is there any difference from autofocus to fixed focus?
24
General / Re: App for circular missions
« on: October 17, 2016, 02:40:53 PM »
Works with the orbitmode of LITCHI, I think.
I guess (but did not try) even with the POI-mode of DJI-GO.
I guess (but did not try) even with the POI-mode of DJI-GO.
25
General / Re: Photoscan DEM bulge-like offset to reference DEM
« on: October 11, 2016, 08:24:17 AM »
I tested it and it works, see this post:
http://www.agisoft.com/forum/index.php?topic=5971.0
Meanwhile I did some more tests (not enough) with this results:
The angle for taking the oblique fotos should be between 30° und 50°.
The AGL for the flight with oblique fotos should be identical to the normal flight plan.
The number of fotos during flight plan (normal angle) shold be significant higher the number of oblique fotos.
It should be the same camera and same adjustments for both flights.
After testing (too few) areas, this seems to bring good DEM-results.
I hope, some more UAV-users try it and tell us about their results.
http://www.agisoft.com/forum/index.php?topic=5971.0
Meanwhile I did some more tests (not enough) with this results:
The angle for taking the oblique fotos should be between 30° und 50°.
The AGL for the flight with oblique fotos should be identical to the normal flight plan.
The number of fotos during flight plan (normal angle) shold be significant higher the number of oblique fotos.
It should be the same camera and same adjustments for both flights.
After testing (too few) areas, this seems to bring good DEM-results.
I hope, some more UAV-users try it and tell us about their results.
26
General / Flight plan against bowl effect
« on: October 07, 2016, 02:23:50 PM »
Maybe this ist of interest for other users:
Thanks @bemis I could read this article:
http://onlinelibrary.wiley.com/doi/10.1002/esp.3609/full
As I often have problems with the bowl-effect when creating DEMs, I tried it out.
First I planed and made an "normal" UAV-flight with 68 nadir fotos.
The result (DEM) was quite poor, with a big bowl-effect.
Then I took 10 more fotos and tilt the camera for 30°.
I alligned the nadir and oblique fotos.
The resulting DEM (78 fotos) did not show the bowl effect.
In the attachments you can see the flight plans, the dense clouds, the DEMs and profiles.
I did not use any GCPs.
It also works wit other tilt-angles of the camera.
Thanks @bemis I could read this article:
http://onlinelibrary.wiley.com/doi/10.1002/esp.3609/full
As I often have problems with the bowl-effect when creating DEMs, I tried it out.
First I planed and made an "normal" UAV-flight with 68 nadir fotos.
The result (DEM) was quite poor, with a big bowl-effect.
Then I took 10 more fotos and tilt the camera for 30°.
I alligned the nadir and oblique fotos.
The resulting DEM (78 fotos) did not show the bowl effect.
In the attachments you can see the flight plans, the dense clouds, the DEMs and profiles.
I did not use any GCPs.
It also works wit other tilt-angles of the camera.
27
General / Re: Photoscan DEM bulge-like offset to reference DEM
« on: October 06, 2016, 02:47:45 PM »
@bemis
Thank you.
The article seems to be very interesting.
But my english is quite poor.
Did I understand correctly, that the bowl-effect ("banana-shape"), that often ist mentioned in this forum, can be minimized by the flight-plan?
First do a "normal" flight with the camera 90° to the ground and then combine it with oblique fotos (camera 20°-30°)?
Thank you.
The article seems to be very interesting.
But my english is quite poor.
Did I understand correctly, that the bowl-effect ("banana-shape"), that often ist mentioned in this forum, can be minimized by the flight-plan?
First do a "normal" flight with the camera 90° to the ground and then combine it with oblique fotos (camera 20°-30°)?
28
General / Re: Using Ground point control is mandatory ?
« on: September 17, 2016, 08:54:05 PM »
Lot of error:
I just made a map with a lenght of about 110 m. The Terrain slightly rises up. The difference from W to E is 1,7 m (manuell measured).
The ortho is perfect, but the DEM shows a difference of 3 m (no GCP).
I usually compare the DEM with manuell measuring.
If I had GCPs, I measure them "old style"
I just made a map with a lenght of about 110 m. The Terrain slightly rises up. The difference from W to E is 1,7 m (manuell measured).
The ortho is perfect, but the DEM shows a difference of 3 m (no GCP).
I usually compare the DEM with manuell measuring.
If I had GCPs, I measure them "old style"
29
General / Re: Using Ground point control is mandatory ?
« on: September 17, 2016, 04:37:27 PM »
You are right, the P3A is cheap drone.
But the results are quite amazing.
Orthofotos (without GCP) have only slightly error, less than expected.
By using GCPs, orthofotos are "perfect".
The problem is the elevation in DEM, for good results GCPs are a must.
I dont think, the reason for this is the "hobby quality" of the phantom.
But the results are quite amazing.
Orthofotos (without GCP) have only slightly error, less than expected.
By using GCPs, orthofotos are "perfect".
The problem is the elevation in DEM, for good results GCPs are a must.
I dont think, the reason for this is the "hobby quality" of the phantom.
30
General / Re: Using Ground point control is mandatory ?
« on: September 17, 2016, 04:20:55 PM »
I am also mapping with a P3A.
My DSM without GCPs are usually quite poor.
The error ist very big and I cannot use such DSM for measurements.
So I think, you must work with GCPs.
My DSM without GCPs are usually quite poor.
The error ist very big and I cannot use such DSM for measurements.
So I think, you must work with GCPs.
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