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Author Topic: before buying some tip for best quality  (Read 11360 times)

alistar

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before buying some tip for best quality
« on: February 20, 2013, 10:49:17 PM »
I'm trying the demo version and I had some issue with the quality of the 3D reconstruction. So here some questions, I found some assessment from people on this forum, but not from agisoft personal, so I would like to hear a bit more about it, to see if I can have it to work for my needs, which would spare me a lot of time :)

some notes : I use a Nikon D90, I used my zoom at 33mm (about 50mm 35mm equiv.), I tried sharp and smooth and reconstruction quality up to very high, followed the rules in the doc for viewpoints. I try to get 3D models of objects with a lot of "branches" (so many parts are hiding other parts)

1. I use Lightroom to save my Raw as Jpg, should i deactivate lens distortion, vignetting and/or Chromatic Aberration correction ?

2. Can I use my zoom at other focal reliably ? Sometime for architecture, only 18mm works. Will the error ratio increase ? I use it for photogrametry and error above 5cm are a big problem.

3. Which format is the best actually ? Jpg, exr, other ?

Just to help for the doc, I use OpenCL on linux with a HD7770 Catalyst 13.2 and it works perfect in all modes until very-high quality for reconstruction (tested with sets up to 32 photos and it's 2x faster than CPU only).

Thanks

David Cockey

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Re: before buying some tip for best quality
« Reply #1 on: February 21, 2013, 12:03:40 AM »
My experience is better results are obtained with PhotoScan if the lens distortion correction in LightRoom, OpticsPro or similar software is not used.

I have experimented with using chromatic aberration correction. Depending on the lens there can be an improvement in PhotoScan results.

Vignetting correction does not seem to have much effect. I have used adjustments during "development" of the RAW photos to improve the amount of detail in shadows and highlights, and this has improved PhotoScan results in some cases. It is good to have reasonable consistency across images.

I use a Canon DSLR with a 18-55 mm zoom lens and a 40 mm lens. The zoom lens is most commonly used at 18 mm (about 28 mm full frame equivalent) and has also been used at 24 mm. The choice depends on the shape of the object being photographed and the amount of space around the object.

I shoot RAW and convert to TIFF with the DSLR. I previously used a camera which only produces JPEG, and I used the highest resolution and quality JPEG available.

alistar

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Re: before buying some tip for best quality
« Reply #2 on: February 21, 2013, 02:11:09 PM »
Thanks for your answer David, I kept reading on other websites whatcam out was :
1- No distortion correction
2- Chromatic aberration correction is good
3- Panasonic Cameras are bad for photogrametry (they have automatic distortion correction activated in raw too).
4- Exr is the best format.

I have a pansonic camera too, so I would be interested on hearing more about those 3 points (True or false ?)
My personal data set (40 photos, 12Mpix) takes 15 hours to be processed, so I hope you understand I don't have time to try every possible combination (distortion on/off, chroma on/off, exr/jpg/png... at least 10 tests with 15 hours per test, that's too much.) ;D

CamKrist

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Re: before buying some tip for best quality
« Reply #3 on: February 21, 2013, 05:23:48 PM »
I sent you in pm

alistar

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Re: before buying some tip for best quality
« Reply #4 on: February 21, 2013, 07:50:33 PM »
sorry if I annoy, but I'm student so I can't easily spend 170 dollars without being sure it will do what I need.
I will shot in scenario where I can't choose the light : I go to a place for 2 hours and have to take make a 3d model of it whatever the weather is like and I can't easily return there after.
So if there are hard shadows, exr would logicaly be the best option to have details in shadows and highlights ?
Is chromatic aberration correction good ? I use a cheap 18-250 lens with pretty much CA at wide angle, does it produces problems for the algorithm ?
It would be practical to use my compact panasonic sometime as the dof is much better for small objects. But if the automatic correction is a problem...
I normally use demo to test such things, but my first test took 15 hours to reach 100% and is locked with high disk utilization since 2-3 hours. So I can't test all possible camera and raw processing configurations.

Wishgranter

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Re: before buying some tip for best quality
« Reply #5 on: February 21, 2013, 08:12:59 PM »
Chroma abbrebation can be removed - no extra related to results
No Distortion remove !! -

Try shoot to RAWs, then export in TIFF 8bit. For model generation its used just 8bit images, for texture can ust 96Bits......

JPGs are "litle" blurred - impact on quality.......
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alistar

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Re: before buying some tip for best quality
« Reply #6 on: February 21, 2013, 10:37:58 PM »
Thanks Wishgranter,
So i just relaunched my test scen without distortion correction, but with CA correction. I hope it will solve the problem. I had to kill the process it went to up 12GB usage and i couldn't use my PC anymore.
Maybe to reduce the memory usage I could rescale to 6Mpix ? My c=body+lens combination doesn't get more than 5MPix on dxomark anyway (poor optic quality) so the extra 6 Mpix are just blur. Is it ok withotu croping ? Will it help to speed up things ? I would like to have quicker test, 15 hours is way to long.

Wishgranter

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Re: before buying some tip for best quality
« Reply #7 on: February 22, 2013, 01:18:02 AM »
Hello Alistar

Its possible to get to lower resolution if its 12 Mpix try rescale to aprox 6-7 Mpix, and try litlle sharpening, not too much..... No crop, no distortion...... try save TIFs not JPGs...
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alistar

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Re: before buying some tip for best quality
« Reply #8 on: February 22, 2013, 01:50:41 AM »
THanks wishgranter :)
Is there a known way to use my panasonic camera ( i.e. distort the image back again). Even the raw are already corrected, I can't deactivate it in lightroom.

Wishgranter

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Re: before buying some tip for best quality
« Reply #9 on: February 22, 2013, 02:47:22 AM »
hmm what precise model of camera you have ?
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alistar

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Re: before buying some tip for best quality
« Reply #10 on: February 22, 2013, 11:19:23 AM »
I have the DMC-FZ150.

Edit : without lens distortion correction it works much better, i'm trying with 6Mpix to see if it is faster and how it affect quality.

Other question : I have very low details in dark area (between stones). I can't solve that and details are in NEF file (visible with tonemapped version.) Is it possible to use a shadow enhancement that is compatible with the algorithm ? Tonemapping certainly not as it works with local contrast but there modifying the tonecurve ? Lightroom lights ? Exr ? Exporting to 16bit/channel tiff I loose that details in photoshop at least (strange as the D90 has only 12bit/channel...).
« Last Edit: February 22, 2013, 01:05:00 PM by alistar »

David Cockey

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Re: before buying some tip for best quality
« Reply #11 on: February 23, 2013, 12:05:31 AM »
You can use LightRoom to adjust the photos so the shadow details show up. Either use the Whites/Highlights/Shadows/Blacks sliders or adjust the tone curve.

Wishgranter

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Re: before buying some tip for best quality
« Reply #12 on: February 23, 2013, 01:01:21 AM »
Use the http://www.dxo.com/intl/photo/dxo_optics_pro/features adn from there teh SingleShot HDR - fully automatic conversion, fast and USEFULL
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alistar

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Re: before buying some tip for best quality
« Reply #13 on: February 23, 2013, 05:50:22 PM »
Thanks to you 2,
I've invested in Lightroom already, DXO will be for after I'm finished with University or I'll have to eat potatoes without butter until the end ^^. Looks like the shadows slide in lightroom works well with photoscan.
For my D90, i can use distorted images, but with my panasonic, does someone know how to deactivate correction ? As said before, Raw are already processed in new panasonic cameras. Or is it a photogrametry-compatible correction ?