Agisoft Metashape

Agisoft Metashape => General => Topic started by: pagan on May 13, 2012, 10:11:12 PM

Title: double-triple allignments
Post by: pagan on May 13, 2012, 10:11:12 PM
Dear all
I would like to know if there is a way to exclude images that cause double allignments or even triple.
Attached you'll see an example
Many thanks in advance
Nic
Title: Re: double-triple allignments
Post by: Wishgranter on May 13, 2012, 10:38:28 PM
Photos need to be shooted for pjhotogrametry, mostly if shoot from low angle - mostly if shooted like panoramatic shoot, from one place and turn around. best is to delete the ones that are very close toggether = one view and 2-more same shots........ can grab the "camera" in Pscan window ???
Title: Re: double-triple allignments
Post by: pagan on May 13, 2012, 11:03:57 PM
Not quite sure that I have understud...
You are saying that close-ups ar not allowed? And will only work if I go around the object including the whole object in every image?
If it is so, it is quite strange because it is occuring to me only for a medium-small objects.
I have done entire walls not including the whole objects and going quite close in order to include details and it worked fine.
But probably you are right I have too many similar shots...I will give it a try...
thanks for the tip!
Title: Re: double-triple allignments
Post by: Wishgranter on May 14, 2012, 01:42:30 AM
im mena similar shots..... post screenshot of the scene in Pscan that is clear to see the cameras - stations of points from where you shoot them.....
Title: Re: double-triple allignments
Post by: FoodMan on May 14, 2012, 08:34:35 AM
maybe not enough overlap..?

f/
Title: Re: double-triple allignments
Post by: pagan on May 14, 2012, 01:15:03 PM
I am quite sure that I have enough overlap even too many maybe.
Could it be that I also have included images where part of the object are sometimes ot of focus?
Title: Re: double-triple allignments
Post by: Kjellis85 on May 14, 2012, 03:11:16 PM
Could you post some of the images that you suspect are causing the error?
Title: Re: double-triple allignments
Post by: pagan on May 14, 2012, 03:31:52 PM
Here is  one , let me know if you need more.
You can see that the right side is out of focus
My method is to do general around object shooting and then I go randomly doing some close-ups for details, however when I go very close sometimes I don't have much depth of field.
If it is this, that is cousing the problem, I could step back a bit an use the zoom, is it ok in the same chunk to change the zoom lens ?
Title: Re: double-triple allignments
Post by: FoodMan on May 14, 2012, 04:11:29 PM
oki.. don't look further.. the dof is responsible..

one way (if you can redo the shooting) is to use Image stacking with Helicon Focus for instance ... I tried.. it works.. although Alexey has not confirmed it is supported..

http://www.heliconsoft.com/heliconfocus.html (http://www.heliconsoft.com/heliconfocus.html)

btw, I am in no way affiliated to Helicon..

f/


edit.. for example, that starfish uses 5 photos from Helicon (out of 25 ) and as you can see it works.

(http://www.divshare.com/direct/17629915-528.jpg)

Title: Re: double-triple allignments
Post by: Kjellis85 on May 14, 2012, 04:14:27 PM
Stepping back could help, but I would suggest using a tri-pod and using a high apperture stop of 11 or higher. This would increase the area of focus substantially. You can use this to figure out your optimal settings. http://www.dofmaster.com/dofjs.html (http://www.dofmaster.com/dofjs.html)
Title: Re: double-triple allignments
Post by: FoodMan on May 14, 2012, 04:16:04 PM
Stepping back could help, but I would suggest using a tri-pod and using a high apperture stop of 11 or higher. This would increase the area of focus substantially. You can use this to figure out your optimal settings. http://www.dofmaster.com/dofjs.html (http://www.dofmaster.com/dofjs.html)

That too.. but that still might not be sufficient..
Title: Re: double-triple allignments
Post by: Wishgranter on May 14, 2012, 05:22:58 PM
hmm yes, focus cause problems. try shot from other angles =  shoot from the corner, it should be much better and set the aperture higher + tripod as mentioned from other here......
Title: Re: double-triple allignments
Post by: pagan on May 14, 2012, 10:20:41 PM
Whoa! thank for all your help!!!
Well... I will give it a try...
I can not really choose the tripod option because I have a very large amount of objects to shoot and that will really slow down the process.
Also helicon looks like you need to shoot even more images.
I would prefer to set up a very well lighted scene instead for medium range distance. Then I should be able to shoot at big f-stops lets's says f11 and keep the speed high(such as 60 so that I don't have to use a tripod) and so everything should be in focus.
Regarding the close-up shots is it ok to change the focal lenght in the same chunk in PS?That I think would give me the oportunity to shoot far back in order to gain more depth of field right?
Title: Re: double-triple allignments
Post by: Wishgranter on May 15, 2012, 01:27:48 AM
Yes, this is peciality of Pscan with different focal lenght, work up around 20mm under this mostly fail apart...... need few tests..... from hand try to get around speed of 200, or dont drink cofee or something cold :-)

and good luck with that......
Title: Re: double-triple allignments
Post by: pagan on May 15, 2012, 01:53:08 PM
Ahhh!
I was working at 18mm so that also may have cause the problem.

(Sorry did not understand you are saying that will not work or that it will work with different focal lenghts?)

Thanks a lot
Title: Re: double-triple allignments
Post by: Wishgranter on May 15, 2012, 02:21:28 PM
mena if go down then a bigger distortion will show up, afther some focal lenght - strong distortion Pscan will not align photos. too big error.....

What type of camera you use ?

18mm but on what camera , if Fullframe like Canon 5D you have 1:1 the focal lenght, on the Canon  APS-C - you get 1.6 the focal lenght of lense.... 18*1,6 = 29mm aproxx...  that mena on Canon 5D you get to limits of waht possible, on APSC it should work....
Title: Re: double-triple allignments
Post by: pagan on May 16, 2012, 01:10:00 AM
I am using a Nikon D3100 with the standard lens 18-105mm

It would be nice to see if PS can work with this http://www.lytro.com/ (http://www.lytro.com/)
Then I think that there will be no more problem of depth of field  :)
Title: Re: double-triple allignments
Post by: Alexey Pasumansky on May 16, 2012, 04:14:24 PM
Hello Nic,

The problem could be in an excessive overlap when some camera locations are too close to each other (for example, if several photos were taken from the same position only by rotating the camera.

Regarding to the different focal lengths, maybe better results could be achieved if the images with the same focal length are grouped together (by order in Workspace). But more stable results would give shooting when focal length is fixed for all the photos.
Title: Re: double-triple allignments
Post by: pagan on May 16, 2012, 05:19:24 PM
Many thanks Alex...
I though that the overlap would have been also the case for the double allignments as I have experienced before. I was thinking if there was a quick way to recognize  what photos is mostly attributed to the wrong allingment so that I can delete them, rather than going through each on  visually.

Also thanks alot for the tip of the focal leght I will try that and if it does not work I will keep the same FL.