Scanning problem: bumps

[YarridHenrard]

Hey!

I was hoping if someone could help me out with this problem that I keep having or explain me why it happens since I cant seem to find out why it keeps occurring. I have some ideas which I should probably resolves while taking the actual pictures but maybe I am just doing something wrong in Agisoft

I keep getting this bump all over the scan :s

[Alexey Pasumansky]

Hello YarridHenrard,

I see the following most probable reasons: lack of texture pattern on the scanned surface and changing shape of the scanned surface, for example, if you are using single camera for living subject scanning.

[YarridHenrard]

Hey Alexey,

Thanks so much for the reply! I really appreciate it to narrow down the possible solutions
The model is a professional live drawing model and is basically perfectly still ( as far as the human eye can notice) but the lack of texture variation is of course true since it is a nude model. However do you maybe know then how they aproach scanning the human body and/or face? I have seen single camera rigs that produce very decent quality without all these bumps.

[Alexey Pasumansky]

Hello YarridHenrard,

I've moved the thread to Face/Body scanning section.

I think that for tests with the single camera you can start with smaller dataset (to minimize the shooting session time and therefore the changes of the body shape) and also use chair or wall to back the scanned person (will help to avoid the smaller movements of the body).

Also check that your images are sharp and focal depth is good enough to avoid the image blur. Additionally you can reduce the ISO value to minimize the image noise.

[YarridHenrard]

Hey Alexey,

Ow okey sorry for putting it in the wrong section

I am testing now with a different set of images that I took and I am still getting the same results. Person was seated on a chair with good light setup and we just quickly took 15 pictures from the front to make it as quick and easy as possible.

Very high-rez images and avoiding any spec.

weirdly enough the shirt is coming out pretty well but the face just gets smashed to bits. Will this still be because of slight movements from the model?

[Alexey Pasumansky]

Hello YarridHenrard,

Usually artifacts that look like the abrupt changes in the geometry for some areas indicates that there are alignment issues - in your case meaning that either the parameters of internal and external camera orientation were estimated incorrectly or the actual distance to the surface of interest has changed. Usually people cannot keep their body static and slight vibration is always present, that's why I suggest to support the head, for example, by the wall, making the position more stable and static.

Also for alignment step I can suggest to disable Adaptive Camera Fitting option and compare the results.

[YarridHenrard]

Hey Alexey,

I will start trying both of them right away! Thanks so much for your help already
Wish I had a budget to setup a multiple camera rig but that is sadly not the case right now xD

[Alexey Pasumansky]

Here are some topics about setups that utilize only a few cameras and a turntable (or rotating rig), so they could be also informative for you.

[ekbmuts]

Hey YarridHenrard,  I'm fairly new to this but all I've done is face and body since I started.  Some things I have learned that might be of use to you:

1.  Shoot RAW as high-res as your camera will go.  Photoscan doesn't support RAW (except I think now .dng is supported) so convert all your images to TIFF in Photoshop, 16-bit and import those files into Photoscan.  I will often also remove chromatic aberration in Photoshop but not much else.  Whatever you do, DON'T do any image manipulations like stretching or scaling or cloning.

2.  If the model moves an inch, it's all over.  At least, you won't get a perfect scan.

3.  Set your ISO as low as you can and your aperture to f11 or better (meaning higher, f16, f22, etc.).  You might need a lot of light for this and that's the downside.  So I'd suggest taking your model outside, on a cloudy day where you can set your camera accordingly.  In a studio with those settings is going to require a LOT of light.

Why these settings:  low ISO eliminates/reduces noise.  High aperture setting increases how much of the shot is in-focus from front to back.  If you're already a photographer and you know this, sorry.  Not trying to talk down to anyone.

4.  Shadows will mess up the scan.  Hard shadows, that is.  You don't want any shadows if you can help it.

5.  Fill your frame.  That is, get right up close to your model.  Don't have her face filling 10% of the picture.   Fill the whole frame.

6.  Make sure every shot is in-focus.  This is where aperture comes in.  If you're shooting at f2.8 (for example) and you're 12 inches from the model, she's not going to be in focus from front to back.  But either way, your shots have to be in focus.  So rather than racing around with your camera in machine-gun mode, take the time to focus and shoot, focus and shoot.  Sure, the model has to stay still for longer.  But that's not too hard if they're supported by something.

7.  Having said that, shoot as quick as you can.  NO ONE can hold still forever.

8.  If you can, to reduce time, get some friends with cameras to shoot at the same time with the same rules as above.  That would cut your shooting time down considerably.  Doesn't really matter if they're all using different cameras.

That's my input.  I finally managed to shoot a ballerina's head with the above things in mind.  Man, she came out PERFECT!  And we shot her with 3 different cameras, 3 different lenses under fairly controlled conditions (she had something to lean on...).

Good luck!

Jon

[YarridHenrard]

Hey YarridHenrard,  I'm fairly new to this but all I've done is face and body since I started.  Some things I have learned that might be of use to you:

1.  Shoot RAW as high-res as your camera will go.  Photoscan doesn't support RAW (except I think now .dng is supported) so convert all your images to TIFF in Photoshop, 16-bit and import those files into Photoscan.  I will often also remove chromatic aberration in Photoshop but not much else.  Whatever you do, DON'T do any image manipulations like stretching or scaling or cloning.

2.  If the model moves an inch, it's all over.  At least, you won't get a perfect scan.

3.  Set your ISO as low as you can and your aperture to f11 or better (meaning higher, f16, f22, etc.).  You might need a lot of light for this and that's the downside.  So I'd suggest taking your model outside, on a cloudy day where you can set your camera accordingly.  In a studio with those settings is going to require a LOT of light.

Why these settings:  low ISO eliminates/reduces noise.  High aperture setting increases how much of the shot is in-focus from front to back.  If you're already a photographer and you know this, sorry.  Not trying to talk down to anyone.

4.  Shadows will mess up the scan.  Hard shadows, that is.  You don't want any shadows if you can help it.

5.  Fill your frame.  That is, get right up close to your model.  Don't have her face filling 10% of the picture.   Fill the whole frame.

6.  Make sure every shot is in-focus.  This is where aperture comes in.  If you're shooting at f2.8 (for example) and you're 12 inches from the model, she's not going to be in focus from front to back.  But either way, your shots have to be in focus.  So rather than racing around with your camera in machine-gun mode, take the time to focus and shoot, focus and shoot.  Sure, the model has to stay still for longer.  But that's not too hard if they're supported by something.

7.  Having said that, shoot as quick as you can.  NO ONE can hold still forever.

8.  If you can, to reduce time, get some friends with cameras to shoot at the same time with the same rules as above.  That would cut your shooting time down considerably.  Doesn't really matter if they're all using different cameras.

That's my input.  I finally managed to shoot a ballerina's head with the above things in mind.  Man, she came out PERFECT!  And we shot her with 3 different cameras, 3 different lenses under fairly controlled conditions (she had something to lean on...).

Good luck!

Jon

Hey Jon!

Thanks for summing all that up for! Very helpful I cant wait to get some time again and start doing some tests... Very sorry for the late reply, it has been pretty busy lately, had to put this project on hold for a while. With some luck I will get back into it this weekend

All your tips will be very useful for then!

Have a wonderful day,
Yarrid

[techead]

Hello

I'd like to know if you managed to come right? I am in the process of doing the same, and also getting a lot of bumps, although we did shoot again recently and its definitely getting better.

What MegaPixel level do you recommend? ISO level?

Also what about focus mode on the camera. I assume center focused would be best, not spot focused?

Hey YarridHenrard,  I'm fairly new to this but all I've done is face and body since I started.  Some things I have learned that might be of use to you:

1.  Shoot RAW as high-res as your camera will go.  Photoscan doesn't support RAW (except I think now .dng is supported) so convert all your images to TIFF in Photoshop, 16-bit and import those files into Photoscan.  I will often also remove chromatic aberration in Photoshop but not much else.  Whatever you do, DON'T do any image manipulations like stretching or scaling or cloning.

2.  If the model moves an inch, it's all over.  At least, you won't get a perfect scan.

3.  Set your ISO as low as you can and your aperture to f11 or better (meaning higher, f16, f22, etc.).  You might need a lot of light for this and that's the downside.  So I'd suggest taking your model outside, on a cloudy day where you can set your camera accordingly.  In a studio with those settings is going to require a LOT of light.

Why these settings:  low ISO eliminates/reduces noise.  High aperture setting increases how much of the shot is in-focus from front to back.  If you're already a photographer and you know this, sorry.  Not trying to talk down to anyone.

4.  Shadows will mess up the scan.  Hard shadows, that is.  You don't want any shadows if you can help it.

5.  Fill your frame.  That is, get right up close to your model.  Don't have her face filling 10% of the picture.   Fill the whole frame.

6.  Make sure every shot is in-focus.  This is where aperture comes in.  If you're shooting at f2.8 (for example) and you're 12 inches from the model, she's not going to be in focus from front to back.  But either way, your shots have to be in focus.  So rather than racing around with your camera in machine-gun mode, take the time to focus and shoot, focus and shoot.  Sure, the model has to stay still for longer.  But that's not too hard if they're supported by something.

7.  Having said that, shoot as quick as you can.  NO ONE can hold still forever.

8.  If you can, to reduce time, get some friends with cameras to shoot at the same time with the same rules as above.  That would cut your shooting time down considerably.  Doesn't really matter if they're all using different cameras.

That's my input.  I finally managed to shoot a ballerina's head with the above things in mind.  Man, she came out PERFECT!  And we shot her with 3 different cameras, 3 different lenses under fairly controlled conditions (she had something to lean on...).

Good luck!

Jon

Hey Jon!

Thanks for summing all that up for! Very helpful I cant wait to get some time again and start doing some tests... Very sorry for the late reply, it has been pretty busy lately, had to put this project on hold for a while. With some luck I will get back into it this weekend

All your tips will be very useful for then!

Have a wonderful day,
Yarrid