How to reconstruct shiny object with Reality Capture

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Dear Friends,
I wish to make 3d model of statue, the problem is surface of statue is shiny. The statue is highly valuable so we can not apply any type of coatings etc. And I wish to make 3d model from photogrammetry with the help of 24mp DSLR camera only.
I found a video on YouTube, In that video , thay have given a way to reconstruct shiny object, but this video is very short and without voice, I also not understand this is related with photogrammetry or 3d Lazer scanner. Youtube web link is -
https://m.youtube.com/watch?v=D7iY146cU2Y

Please guide us in details as early as possible , I am new in RC, so please guide from basic but I am familiar with photogrammetry with other software like 3df Zephyr and Recap

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Hello Yogesh,

that video is related to this article: http://janebeecr.blogspot.com/2017/07/how-to-scan-shiny-surfaces.html

In this article you can find the instructions how to use coating spray when taking pictures of shiny surfaces.

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Yogesh,
You can try a polarizing filter. If you can minimize the glare enough RC is usually able to piece things together.
Baby powder is the only other thing I could think of. I know you said you can’t coat it, but maybe you could get away with a light dusting that is easily removed.

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For very valuable items, you can’t do much. Photogrammetry shows its limits with these kind of objects… That is why your video was talking about laser scanners. There are usually better than photogrammetry with these kind of objects.

If the object is not too black or not too mirrorish, you can try to projet a pattern of chromatic noise with several video projectors, I had some success with that with hard to reconstruct objects. But this depends. Do you have a picture of the statue ? What surface material is it ? What color ? 

 

 

 

 

 

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Of course if you have some surface detail (like on some kind of multi-color polished Marbles), the reconstruction will be fine even if the objet is very shiny. Did you try ?

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Respected Friends,                 

Thanks to all for reply,

@ Zuzana Ďuríčková CR  -   Thanks to share proper information on that video.

@ Steven Smith   -  Thanks for your guide, I will do photography with polarizing filter, use of Baby powder is good idea, but not possible at least for current object. Well thanks.

@ Jonathan_Tanant  -  Sir, really there is limit of Photogrammetry for shiny object. I tried to think on laser scanners under $1000, I checked some laser scanners product with their sample 3d model , I found that there resolution is very low, e.g. eyes of human face in model look in round shape only. If possible than Please suggest great resolution laser scanners under $1000.

I am new in 3d model, but I observe in Photogrammetry that we can greatly improve resolution by using very sharp proper photography , but I think in laser scanners we cannot go above a limit which is a low resolution at end.

Well, Object is not too black and not too mirrorish. But I don’t understand concept of “projet a pattern of chromatic noise with several video projectors”, Please guide on that.

The image is given below. Material is plastic.

My rough plan is -  use polarizing filter , use of rotating table technic , use 24mp camera with stand, high aperture between 16 to 22, ISO 100 to 200, shutter speed according to camera exposure that’s may be 1 to 2 sec due to low light, low intensity diffused focus, location of focus at behind statue so statue will receive more defused light through wall and no angle of reflection will create between camera and source of light , after making 3d model use Zbrush to clear errors. Please guide more on set up.

I am thinking on some points, we see object at original color, but we also see some shiny noisy white light spot on object , I am thinking that how we can separate and subtract non required color from white shiny spot.

I am thinking that, use of any one or two color (e.g yellow/red/blue etc) diffused focus, so few colors directly absent from source of light, so I think shiny spot will not look white and noise on that spot will reduce  . . . etc , but how RC will react I dont know . . . . I will share my result with more ideas. 

I hope, all of you will also guide on that points and rethink on different solution of shiny object again and please share.

Thanks to all . . . . May all happy !

 

 

  

 

 

 

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If you intend to use a turntable I highly recommend also using a lightbox or light tent. Those are specifically built to provide a lot of diffuse light from all directions to eliminate shadows and glare.

The added benefit is that the background will have no features that RC can latch on to for alignment.

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Yes, you are right about scanners, there are really not cheap if you want good results and we all like the super scalability and cheapness of photogrammetry here ! you can really push the limits with “reasonable” investments and training.

I think it can definitely work, there is some detail on the statue that can help.

I would not work with a turntable - my experience with that is that when you have an object that is a bit limit (too shiny, not enough features), this is worst when using the turntable. 

You need to put a lot of fully featured items all around the statue : use newspapers, magazines, (just be sure they don’t move)… this will help alignments.

I would not work above f/16. It depends on your lens of course, but at f/16 and f/22 you have a big loss of quality (diffraction) - especially if you are at 100 iso on a tripod… You have to do some tests to find the best tradeoff between depth of field and sharpness - some where between f/5.6 and f/11.

Work at a fixed white balance (measure it on a chart if you want a good accuracy)

And, very important, take a lot of photos with great overlap. All around, then closeup details.

Don’t forget to include a scale or a visual with known markers, where you can put a reference distance.

 

The pattern of chromatic noise consist of :

-generate a picture of chromatic noise in GIMP : you will end up with a pattern of unique dots of random colors.  You can experiment with several settings for resolution, density of noise, size and upscaling (I usually generate a 960x540 pattern that I upscale in nearest mode to a 1920x1080 to have 2x2 colorfull tiles)

-use a video projector to project on the piece. Find the best position to have a sharp projection on the piece.

-You will maybe need several projectors (in that case, you need to generate other patterns, do not reuse a pattern).

-take pictures all around with and without the pattern videoprojection.

-align pictures.

-use the pictures without the pattern to texture.

The pattern of chromatic noise really helps RC to understand the surface (because this is a lot of unique features) and achieve much better accuracy. Maybe I will write some tutorial if more people are interested in the technique.

 

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Based on my (quite limited) experiences you should not have a problem with reconstructing this sculpture. As long you are using a proper diffused light setup for it (you could build a tent around the sculpture fx.) you should be able to scan them with high quality camera equipment.

Look at my take at jewellery:

https://www.youtube.com/watch?v=8UUrj4HbBm8

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Dear Friends,

@ ShadowTail - Thanks for your guideline.

@ Jonathan_Tanant - Sir, heartily thanks for your help, well regarding aperture - You are correct that f/16 to f/22 really a big loss of quality due to diffraction and f/11 is best as I test. Now I am facing problem of bad depth of field, to minimize that problem one solution is use high aperture (f/16 to f/22) for infinity depth, but in this range big loss is quality due to diffraction of light. I will experiment soon use of polarizing lens, may be polarizing lens may help in diffraction light problem due to very high aperture. I have no experience but I think another solution is use of micro lens, I think we will get sharp image with infinity depth from micro lens especially in the view of small object close photography. Sir I am new in photography and photogrammetry, Please guide us with your valuable experience.

Please light on topic of “include a scale or a visual with known markers”

The pattern of chromatic noise really a good technique, where without touching of object we will get best reconstruction results, I request to you that please write some tutorial on that, this is very innovative technique and unknown for most of peoples. Use of video projectors is perfect but projectors are costly item, can we think any alternative low cost solution to create chromatic noise on object may be by use of Laser led light with there lens or any other think etc.

@ sairus.tro - Sir, I highly impressed by your great work, I request to you that please share your camera set up which used for your shared work. e.g. camera and lens, aperture, ISO, white balance etc … . . . please.

Thanks to all  . . . . . !

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Hi Yogesh!

How big is the sculpture you are working with?

I am using a standard 18 megapixel Canon 600D with macro extension tubes and a vintage 135mm lens. Nothing fancy, I am even shooting at f16.

I am not an expert at photogrammetry yet, but I am willing to share my knowledge if interested. Send me a mail to laszlo@northernlayers.com and we can have a skype / whatsapp meeting.