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Author Topic: Bumpy suface  (Read 18946 times)

Brit

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Bumpy suface
« on: September 14, 2014, 10:53:32 PM »
The higher the cloud density, the more bumpy the surface. Does anyone know why. Also, how would I improve the quality? I have uploaded 4 images. One is an image of the original sculpture (with white where the mask is). The second (that looks like porcelain) was form Catch 123, the second (less bumpy) was using high quality dense loud and the third using a ultra high cloud (very bumpy). I can't remember but I don' think I reused the map.

bigben

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Re: Bumpy suface
« Reply #1 on: September 15, 2014, 12:11:55 AM »
You're also increasing the resolution of the surface, so you will also start to see more noise. This will partly be related to the distance at which you photographed the object, so if you want a smoother model it's easiest to move closer to the object, remembering that you don't have to include the whole object in each image.

Using gradual selection to delete "bad" points from the sparse cloud can also improve the result. As a quick starting point I use 0.5 for reprojection error and 35 for reconstruction uncertainty

FoodMan

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Re: Bumpy suface
« Reply #2 on: September 15, 2014, 08:31:46 AM »
how many images are you using..? what res..?

f/

Brit

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Re: Bumpy suface
« Reply #3 on: September 15, 2014, 01:40:12 PM »
I used 49 images at 10 mega-pixels in raw format. The statue was high up so this is a close as I could get. I'm not sure what "I use 0.5 for reprojection error and 35 for reconstruction uncertainty". means? ......I just found it on the Help for the software...and I'll try an digest it later. Where do you find these settings? The Help guide doesn't say.

FoodMan

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Re: Bumpy suface
« Reply #4 on: September 15, 2014, 02:26:46 PM »
mmm 10 mpixels is pretty low considering the statue fills only 30% of the images...

f/

bigben

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Re: Bumpy suface
« Reply #5 on: September 15, 2014, 05:16:32 PM »
It's mentioned in the Help under Editing Point Cloud
View sparse point cloud
Menu: Edit > Gradual Selection
Move slider to desired level
Delete the selected points.
Build dense point cloud
(You need to do this separately for each criterion)

Given the size and number of images I think you may be close to as good a result as you can expect though.

chrisd

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Re: Bumpy suface
« Reply #6 on: September 15, 2014, 07:43:10 PM »
Given the size and number of images I think you may be close to as good a result as you can expect though.

Given that the size of the object cannot be increased in the frame, do you have an idea of how many more pictures might improve the result. Like 2x as many, 3x as many, etc?

bigben

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Re: Bumpy suface
« Reply #7 on: September 16, 2014, 12:30:33 AM »
It's the combination of factors...  If it's a single row of photos (i.e. you can't get a higher view) then the number of photos is OK, in which case it's the size of the images (or rather the size of the statue within the images) that is the limiting factor and taking more photos won't get you any significant improvement.

If you could zoom in more that would increase your effective resolution, remembering that the entire object doesn't need to be visible in the frame

Alexey Pasumansky

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Re: Bumpy suface
« Reply #8 on: September 16, 2014, 09:40:57 AM »
Hello Brit,

We are currently checking this dataset. It seems that many images have different size - were they cropped prior to processing?
Best regards,
Alexey Pasumansky,
Agisoft LLC

Brit

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Re: Bumpy suface
« Reply #9 on: September 16, 2014, 03:34:19 PM »
Yes they are cropped for the statue to fit as much as possible of the frame. Is cropping incorrect? I am in the middle of cropping and making 80 images of the Birkenau Gate. It has taken hours. (I hope I don' have to retrieve the originals...if I still have them, and start over.)

Brit

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Re: Bumpy suface
« Reply #10 on: September 16, 2014, 04:10:19 PM »
Sorry I meant "masking", not "making". I did save the originals, so I'll hold off to get the answer (to whether not to crop) before masking and cropping the rest...

...I just read the instructions on the PDF and it says "Do not crop or geometrically transform the images". yikes. I guess I have to start over masking? The gate is quite small in some images since there were obsticals in the way, and it was especially small in the frame when the long wide gate was taken at the side view.

Brit

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Re: Bumpy suface
« Reply #11 on: September 16, 2014, 05:04:29 PM »
here are 2 images (misspelled) before ...and after they were cropped and masked (saved as jpgs and downsized to 110 ppi  to upload here). Should I redo them without cropping?

Alexey Pasumansky

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Re: Bumpy suface
« Reply #12 on: September 16, 2014, 05:49:03 PM »
Cropping is strongly unrecommended.
Best regards,
Alexey Pasumansky,
Agisoft LLC

DCK

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Re: Bumpy suface
« Reply #13 on: September 16, 2014, 08:58:42 PM »
bigben (and others),

really useful post. thanks.

do you use the "image count" criterion on gradual selection? at all levels, it seems to want to remove a very substantial number of points from the sparse cloud.

also, anecdotally, i get the sense that when part of the object is out of focus and not excluded by masking, this affects the quality of the texture model moreso than the geometric accuracy of the mesh. is this correct?

Brit

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Re: Bumpy suface
« Reply #14 on: September 16, 2014, 10:46:39 PM »
Oh well, back to the masking. I'll start over ...I had finished 20 out of 85 images (in 2 hours). Hopefully I'll be faster this time around.