16
General / Anyone tried Mars stereo pairs?
« on: July 03, 2014, 01:49:21 AM »
Just curious if anyone's tried processing images from here: http://www.uahirise.org/stereo_pairs.php
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17
General / Re: low details when exporting model from photoscan, please help
« on: June 30, 2014, 11:58:30 AM »
You should be getting the same number of faces in your exported model as reported in Photoscan.
18
General / Re: Clarification of Reconstruction uncertainty
« on: June 25, 2014, 01:04:54 AM »
Yeah that is a beautiful scan ozbigben! What kind of scale is that?
Thanks. It's about 1.5m high. I've made a number of attempts including 123D Catch but this is the first time I've managed to get the sphere to work. The metal rings are just under 1cm thick and without sufficient points on opposite surfaces you get holes, which has usually meant losing the top 2/3 of the sphere.
19
General / Re: Clarification of Reconstruction uncertainty
« on: June 24, 2014, 02:42:34 AM »
Here's my first test on a DSLR image set (Canon 5D mkIII, 50mm macro, 160 images) for an object, an armillary sphere. There are a few gaps I have to go back and fill in (must stop rushing these in my lunch break) but it's looking awesome so far. Generating a mesh was problematic even with a medium dense cloud, had to go up to high giving me 49M points.
20
General / Re: Clarification of Reconstruction uncertainty
« on: June 24, 2014, 01:55:39 AM »
Thanks for the effort James 
To some extent I like to understand the technical bits so that I can understand how to use them, and in the absence of exact answers I also go by observation. Using similar image counts and settings for generating sparse point clouds I'm finding that I'm using similar thresholds for uncertainty regardless of the camera used. Given the wide range of values for this error I was initially reluctant to drag it so far across to the low end. With image sets in the range of 120-200 for objects I'm finding 30-50 to be practical.
Looking at the points that get removed, I'm thinking it would be nice to be able to filter the dense cloud in the same way.
To some extent I like to understand the technical bits so that I can understand how to use them, and in the absence of exact answers I also go by observation. Using similar image counts and settings for generating sparse point clouds I'm finding that I'm using similar thresholds for uncertainty regardless of the camera used. Given the wide range of values for this error I was initially reluctant to drag it so far across to the low end. With image sets in the range of 120-200 for objects I'm finding 30-50 to be practical.Looking at the points that get removed, I'm thinking it would be nice to be able to filter the dense cloud in the same way.
21
General / Re: Clarification of Reconstruction uncertainty
« on: June 23, 2014, 07:20:18 AM »
I was basing this on the points that were selected after removing reprojection error > 0.5 It's probably a combination of both in the case of the GoPro, and possibly more appropriate to say that the uncertainty seems to be higher when the matching points are near the edges of all matching images. You'll see this with pretty much any lens once you select a low enough uncertainty threshold. especially around the edges of a scene (or the outer edges of an aerial grid).
22
General / Re: Clarification of Reconstruction uncertainty
« on: June 23, 2014, 04:04:07 AM »
You have more matching points but if you project back from a point to it's theoretical position in an image, a small error in the angle will result in a larger error for more distant points. The wider the fov of the lens, the greater the distance of points at the edges tends to be, so you would expect to see higher uncertainty errors at the edges. This is certainly apparent with the GoPro image sets I've been using. As you get to very low values for uncertainty it acts like a depth filter as you can see in my screen grabs. This might be useful for refining the camera positions for an object if you haven't masked the object. It also picks out points that are relatively distant above/below surfaces.
I'm only using the standard version at the moment so it just removes some of the cameras that have a high proportion of bad points, but it's a noticeable improvement. Now for the notes I was writing while people were also replying...
Didn't have time to do some screengrabs before heading off to work but the models had finished.
The differences were subtle at times, but significant enough.
Raw dense point cloud used 90% of cameras. Other combinations of settings I used only lowered this by another 10%. Dense point clouds only varied by about 10% in number of points, but this would have also been due to a reduction in noise.
The addition a low reconstruction uncertainty threshold along with a low reprojection error: reduced noise in underexposed areas, reduced the number of small floating artefacts, removed areas of high noise in flat surfaces, better definition of small protrusions of the object (e.g. tips of the owl's ears)
I also had a brief look at gradual selection based on the image count, but that ended up removing too many cameras when used in conjunction the other two settings but there are probably other circumstances where this would be useful.
Now it's going to be a case of fine tuning the balance of settings, although I think the values for uncertainty used will vary a bit for objects depending on the relative camera positions and fov of the lens but this could possibly be determined by starting with just a few images.
I'm only using the standard version at the moment so it just removes some of the cameras that have a high proportion of bad points, but it's a noticeable improvement. Now for the notes I was writing while people were also replying...
Didn't have time to do some screengrabs before heading off to work but the models had finished.
The differences were subtle at times, but significant enough.
Raw dense point cloud used 90% of cameras. Other combinations of settings I used only lowered this by another 10%. Dense point clouds only varied by about 10% in number of points, but this would have also been due to a reduction in noise.
The addition a low reconstruction uncertainty threshold along with a low reprojection error: reduced noise in underexposed areas, reduced the number of small floating artefacts, removed areas of high noise in flat surfaces, better definition of small protrusions of the object (e.g. tips of the owl's ears)
I also had a brief look at gradual selection based on the image count, but that ended up removing too many cameras when used in conjunction the other two settings but there are probably other circumstances where this would be useful.
Now it's going to be a case of fine tuning the balance of settings, although I think the values for uncertainty used will vary a bit for objects depending on the relative camera positions and fov of the lens but this could possibly be determined by starting with just a few images.
23
General / Re: Clarification of Reconstruction uncertainty
« on: June 23, 2014, 12:13:58 AM »
Thanks James, that makes sense.
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General / Re: Clarification of Reconstruction uncertainty
« on: June 22, 2014, 02:10:35 PM »
I'm using lower quality images specifically to have a wider range of errors and making any improvements to the mesh more obvious... although the iPhone is giving pretty good results (using PureShot to get dRAW TIFF). With DSLR images the differences are more subtle.
I'm running the dense cloud and mesh creation on 4 variations of the same sparse point cloud to see where/if the improvements are more obvious. I've started saving the console output with these tests to have a look at later but this lot won't be finished until tomorrow night.
I'm running the dense cloud and mesh creation on 4 variations of the same sparse point cloud to see where/if the improvements are more obvious. I've started saving the console output with these tests to have a look at later but this lot won't be finished until tomorrow night.
25
General / Re: Ground Control Points and their use
« on: June 22, 2014, 11:58:05 AM »
Yes, you add points to the photos.
http://www.agisoft.ru/tutorials/photoscan/06/
http://www.agisoft.ru/tutorials/photoscan/06/
26
General / Re: Clarification of Reconstruction uncertainty
« on: June 22, 2014, 11:42:46 AM »
I ran some comparison tests using gradual selection for one variable only and looking at the stats for the resulting point cloud. I did this for an image set from my GoPro and iPhone, the iPhone image set is the one in the attached images. Clearly reconsruction uncertainty and reprojection error are completely unrelated so removing bad data points from each is beneficial.
The screengrabs show the final sparse point cloud. Notice that all of the distant points had relatively high reconstruction uncertainty but not necessarily a high reprojection error. The questions that remain for me:
* How do I judge when there are too few points in the sparse point cloud?
* What values for reconstruction uncertainty can be considered "good"?
* Is reconstruction uncertainty related to source image size?
Getting the reprojection error down in the sparse point cloud also seems to speed up the dense point cloud creation. Using a drastic reduction of just reconstruction uncertainty usually increases the mean reconstruction error for the remaining points and generating the dense point cloud was taking ~10-15x longer than other gradual selections.
The screengrabs show the final sparse point cloud. Notice that all of the distant points had relatively high reconstruction uncertainty but not necessarily a high reprojection error. The questions that remain for me:
* How do I judge when there are too few points in the sparse point cloud?
* What values for reconstruction uncertainty can be considered "good"?
* Is reconstruction uncertainty related to source image size?
Getting the reprojection error down in the sparse point cloud also seems to speed up the dense point cloud creation. Using a drastic reduction of just reconstruction uncertainty usually increases the mean reconstruction error for the remaining points and generating the dense point cloud was taking ~10-15x longer than other gradual selections.
27
General / Re: why is my point and shoot making batter captures than a DSLR
« on: June 22, 2014, 09:38:44 AM »@Chadfx, the labeling should be correct; the "IMG_" is from my point and shoot and the "DSC_" is from my new DSLRI'm guessing chadfx based that on the image quality. I thought the same thing but there was no metadata in the smaller images to confirm. The different combinations of camera settings made your point and shoot images better than your DSLR images.
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General / Re: why is my point and shoot making batter captures than a DSLR
« on: June 22, 2014, 05:25:42 AM »
OK, saw this in a different thread 
Nikon D3200, 1/60 @ f20, 6400ISO, 60mm, Delay, AUTO ISO
The images look a little soft, particularly DSC_0019
Canon Powerdhot SD1200, 1/15 @f2.8, 80 ISO, 6.2mm, macro mode, self timer 2s
So as people have suggested here, switch to manual and drop the ISO. Even back to 400 will give you a much better image. I'd probably open up to f11 as well. f20 seems to be killing the sharpness which could also be bringing the noise more into play. If you switch to portrait rather than landscape you can fill the frame a bit more as well.
https://dl.dropboxusercontent.com/u/68078527/DSC_0019.JPG
https://dl.dropboxusercontent.com/u/68078527/DSC_0041.JPG
The top 2 are DSLR
https://dl.dropboxusercontent.com/u/68078527/IMG_4920.JPG
https://dl.dropboxusercontent.com/u/68078527/IMG_4921.JPG
I definitely use a tripod with a self timer. Thanks again for all the response, I am desperate to get it right! And BTW, agisoft software is a life changing event for me!
Nikon D3200, 1/60 @ f20, 6400ISO, 60mm, Delay, AUTO ISO
The images look a little soft, particularly DSC_0019
Canon Powerdhot SD1200, 1/15 @f2.8, 80 ISO, 6.2mm, macro mode, self timer 2s
So as people have suggested here, switch to manual and drop the ISO. Even back to 400 will give you a much better image. I'd probably open up to f11 as well. f20 seems to be killing the sharpness which could also be bringing the noise more into play. If you switch to portrait rather than landscape you can fill the frame a bit more as well.
29
General / Re: How far can a GoPro go...
« on: June 22, 2014, 05:02:25 AM »
Ask them for some full resolution 85° sample images. That will help you make a more informed decision.
30
General / Re: why is my point and shoot making batter captures than a DSLR
« on: June 22, 2014, 04:56:44 AM »
It would be helpful to see the full resolution images if you can post them somewhere else and link to them here, or post a 1:1 crop of the object and some background. The DSLR image has a greater depth of field but it also looks like there's more ISO noise which could be creating false points. Apart from the the shooting suggestions others have already mentioned you may find refining the sparse point cloud may help.
View the sparse cloud
Edit > Gradual selction
With Reprojection error selected as the criterion, move the slider down to give a level of 1 and press OK
Delete the points
Do another gradual selection using Reconstruction uncertainty as the criterion and set a level of 100
Delete the points
Generate a dense point cloud
The other thing I can suggest is having the object on a flat table rather than trying to isolate it. I usually sit objects on something that will raise them sightly above the table top to make it a little easier to remove the table. Have a detailed background on the table (newspaper is good). This provides more information for PS to reconstuct the 3D scene using points closer to the camera. The way you have your object set up it's possible that you are getting more points in the background, however these will tend to have higher error values which in turn will decrease the accuracy of the resulting dense cloud. Having more points in the vicinity of the object will increase the accuracy.
Here's a frame from each of 3 captures I recently did testing an iphone as a camera. After generating the dense point cloud it's relatively easy to remove any unwanted points before creating a mesh.
View the sparse cloud
Edit > Gradual selction
With Reprojection error selected as the criterion, move the slider down to give a level of 1 and press OK
Delete the points
Do another gradual selection using Reconstruction uncertainty as the criterion and set a level of 100
Delete the points
Generate a dense point cloud
The other thing I can suggest is having the object on a flat table rather than trying to isolate it. I usually sit objects on something that will raise them sightly above the table top to make it a little easier to remove the table. Have a detailed background on the table (newspaper is good). This provides more information for PS to reconstuct the 3D scene using points closer to the camera. The way you have your object set up it's possible that you are getting more points in the background, however these will tend to have higher error values which in turn will decrease the accuracy of the resulting dense cloud. Having more points in the vicinity of the object will increase the accuracy.
Here's a frame from each of 3 captures I recently did testing an iphone as a camera. After generating the dense point cloud it's relatively easy to remove any unwanted points before creating a mesh.
