Chaos Corona Forum
General Category => Off-Topic => Topic started by: dubcat on 2015-07-31, 17:01:42
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I had some cheap 3D glasses laying around after last cinema visit. I tore them apart and taped one of the glass parts onto my flash. The other part was handheld, since I have to rotate it 90 degrees. Thought I could share the results in case someone are interested.
The first picture is about 50% diffuse and 0% specular
The middle picture is around 38-50% diffuse and 76-100% specular
The last picture is 0% diffuse and 100% specular
Some of the results are more interesting than others. The cement result is interesting.
I'm thinking about getting some proper filters, could get some really good spec/bump maps from the 100% spec pictures.
The pictures are save as 5Q jpg, the forum has a 30mb upload limit.
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Did you invent this yourself? :D
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Did you invent this yourself? :D
I read THIS (http://filmicgames.com/archives/233) article 5 years ago. Using cheap 3d glasses instead was something I came up with myself.
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I forgot these.
Funny how the handbag looks dirty as hell without spec.
And here is a test I did to see how desaturated a normal image is from the real diffuse
(http://i.imgur.com/v2KJPjw.jpg)
(http://i.imgur.com/I9TPKzu.jpg)
I'll buy a new tripod. If there are any specific materials you want to see, just leave a comment.
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This is crazy. I would have never thought you can do this yourself at home. It actually gets me really interested in capturing custom textures.
BTW that plush companion cube.... <3 <3 <3 <3 <3 <3
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This was a test to see how stuff with SSS behaved. I found this really hairy disgusting soap under my bathroom sink.
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I think I have polarizing glasses from cinema somewhere.......
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I disassembled few lcd screens last year, so i have plenty of polarised film. Did take some pictures with them to get specular free textures. Never knew i can use it to get specular component out of pictures, though. But how do you apply a math expressed in aforementioned article? Through photoshop layer blending perhaps?
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I shoot RAW in full manual mode. Then I import the pictures into Photoshop and in 32 bit mode use (Subtract). It has to be the Albedo that is subtracted from the specular.
I turned the specular to black and white to see how the result would be.
Added picture of my new kit. I read somewhere that it had to be linear filters. Guess it was a lie, because I get the same result with my new circular filters.
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I've upgraded my kit again. The camera flash was too harsh and gave me problems when the room was too dark, since I need longer shutter. I have mounted a 110 lumen LED flashlight with parchment paper in front to diffuse the light.
I took some test pictures of an old white wall, the pictures are calibrated with ColorChecker this time. The only light source was the LED flashlight, 3 sec shutter.
I want to diffuse and spread the light even more, maybe I can add another layer of paper or fabric.
Fascinating how the 100% spec maps show dirt that you normally don't see in real life.
I think the paint is "Egg White", after calibrating the pictures the paint ended up as 168-169 RGB.
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Added picture of my new kit. I read somewhere that it had to be linear filters. Guess it was a lie, because I get the same result with my new circular filters.
I don't think it's a lie. Circular polariser has additional filter glued to it, which changes polarisation. So the one that is attached to light source should be linear to get best results... unless you mount cir-pol filter in reverse (i.e. inner thread pointing to light source), that maight work :] What kind of polariser is attached to camera lens doesn't really matter.
I've upgraded my kit again. The camera flash was too harsh and gave me problems when the room was too dark, since I need longer shutter. I have mounted a 110 lumen LED flashlight with parchment paper in front to diffuse the light.
I took some test pictures of an old white wall, the pictures are calibrated with ColorChecker this time. The only light source was the LED flashlight, 3 sec shutter.
I want to diffuse and spread the light even more, maybe I can add another layer of paper or fabric.
Your LED flashlight has smaller surface area, so it should give you even harsher light. Also camera flash has 100% CRI, while LED gives you 80-90% at best. You want highest possible CRI for that kind of job, i guess. I'd stick with flash. Go full manual and you'll be able to find aperture and flash output combination that gives correct exposure in pitch dark room. Also set widest possible zoom on flash and use built in diffuse filter if 430 ex has such to eliminate vignette.
I shoot RAW in full manual mode. Then I import the pictures into Photoshop and in 32 bit mode use (Subtract). It has to be the Albedo that is subtracted from the specular.
I turned the specular to black and white to see how the result would be.
Somehow i think that math in Filmic games article is a bit more complex than that, but that is just my personal opinion not based on experience :]
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Thanks for the feedback. I will tape one of the 3D glasses onto the flash again and test the setup you are talking about.
The math is 100% the same as filmicgames script, it just looks intimidating since he has to convert between Linear and sRGB, attached comparison image.
I will post the flash results when they are done.
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Here are the results from the flashlight/circular vs flash/linear test.
There is still some spec left in the flash/linear albedo, this is my fault, I didn't notice it before I opened the picture in Photoshop.
The pictures are not ColorChecker calibrated.
The nice thing about the flashlight is that I can use "Video" mode to tweak the filters, while with the flash I have to take a picture and look at the results.
This test was in a pitch black room, I'm going to compare them outside soon. There is a thunderstorm outside right now, so if I don't reply I've been struck my lightning and bitten by a cobra.
EDIT: So i did some tests outside. Only the flash version works, we need a bright light source.
Conclusion:
Dark room = Doesn't matter, easier to use flashlight because of video mode.
Bright room or outside = Flash
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This is great stuff dubcat. I read the same article and I wanted to buy a filter for the lens, but in this case what type of 3D glasses did you use?
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This is great stuff dubcat. I read the same article and I wanted to buy a filter for the lens, but in this case what type of 3D glasses did you use?
It's those standard cheap plastic glasses that you get from the cinema when you are watching 3D movies. The circular filters are HOYA CIR-PL filter, paid around 22€ each, they are very hard to turn.
Attached a crappy mobile picture of it.
Edit: I would recommend attaching the filter to something, your fingers get really messed up after a while. I have taped mine onto a latte spoon.
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Thanks dubcat. 22€ is not that a bad price for a filter. I will follow closely this thread since this was something I really wanted to do after reading that article.
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Thought I could share the "camera flash"/linear results I got after running around like an idiot in the thunderstorm. There is too much wind to capture any vegetation right now.
The pictures you see are Albedo / Normal Picture / Specular
I'm kinda amazed by how much spec these old bricks have
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I've been thinking about building a normalmap scanner box. My idea right now it to buy a cardboard box and glue some LED stripes on each side. Cut a hole in the box to put my camera lens inside, and then have a switch to turn each LED stripe on/off.
I did a test today with my little 110 lumen flashlight, the flashlight was hand held, crappy result, but it gave me some feedback on how I'm going to build the box.
The Illidan test is with the ceiling lamp on, I wanted to see how other light sources affected the result.
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Heh I like you a lot :- ).
Basically you want to build a cheaper scanner like the QUIXEL guys did for their Megascans.
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Basically you want to build a cheaper scanner like the QUIXEL guys did for their Megascans.
Yes, except I don't have to travel to Pakistan and drive into the desert at night (https://www.youtube.com/watch?v=8alYZgkwClM) :)
I've been playing around with light intensity this evening, it has always been a pain in the ass. Is the intensity too strong ? Is the exposure wrong ?
It began with me measuring my nifty little LED flashlight. The opening is 2.5cm, 110 Lumen / 9350 Candela.
I took my ColorChecker, flashlight, camera rig and turned the lights off. I placed the ColorChecker 40cm away from the flashlight and used 100 ISO / 8 shutter / 8 aperture.
I went into 3dsmax and made a Disk light, 1.25 radius, 110 Lumen, same camera settings, and guess what. It looked like a nuclear bomb had gone off.
I faced the flashlight towards the camera and made a 14 stop HDR. In 3dsmax I made a 2,5cm plane and used the HDR as light source. A 13x9 plane with 149 RGB, 40 cm away from the light, that's the same as the ColorChecker. After some interactive rendering tests, the material intensity was 0.017.
The equivalent Disk light is 34 Lumen, and not 110 as the package suggest.
I've also matched the cone direction of the light.
Now I can capture the specular maps with the flashlight, and match them in 3dsmax with the same light setup! Woho
I'm sharing the HDR here if you guys want a calibrated flashlight. Just remember to change the intensity to 0.017 and direction to 0.5
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Until now, all the pictures I have posted have only been for reference. Ugly vignetting, only a little spot of specular. Useless for texture work.
But there is a little secret to overcome these problems, it's called "Lighten".
I have taken some pictures of a chimney that looks like it's been painted with shit.
This is how it works:
1. You move your light source around the room and take multiple pictures. You will get better result the more pictures you take.
2. Copy all the pictures into the same document in Photoshop and set "Blend Mode" to "Lighten" on all the layers.
Right now there are some errors in the maps, this is because it's impossible to hold the light in the correct angle in all the photos. I hope this problem will go away when I have built my cardboard box scanner.
I tried a quick render test to see how the maps reacted to sunlight and a spotlight. The workflow is not production ready, but it's a start. The normal map scanner will take it to the next level! (It's using bump map, displacement doesn't work after last daily)
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Yeah, cross polarized is so nice, it change the way I thnik about textures and blow my mind when saw it first time three years ago, here is the link to topic about it at cgfeedback: http://www.cgfeedback.com/cgfeedback/showthread.php?t=1854
I also attached my tests, shoot on canon 40d with m42 lens
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Yeah, cross polarized is so nice, it change the way I thnik about textures and blow my mind when saw it first time three years ago
Have you had any luck converting the specular over to reflection ? As you guys have seen, when we subtract the 100% spec 50% diffuse from the 50% diffuse, we get an inverted color 100% specular map. I had a look at ICTs reference pictures the other day, and after some testing I found out that they have applied "-100" Saturation" and then "-1.05 Exposure" to the 100% specular pass. But the reflection map that they have created from those photos are around 214 RGB Median. Maybe they have used the high pass technique that I posted a guide on. I haven't had enough time to play around with it yet.
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I began porting Emily 2 over to Corona because I need a good base shader for my future head scans. My vacation is over so I only had an hour to work on this today, the reflection element still need a lot of work. I can share the shader when I feel it is matching the reference.
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Hey Dubcat, lately I have been running trough all your posts as you seem to be endless repository of knowledge and scientific tests.
The first picture is about 50% diffuse and 0% specular
The middle picture is around 38-50% diffuse and 76-100% specular
The last picture is 0% diffuse and 100% specular
According to this, viewing the picture with the fur, in the first picture, there is a visible reflection on the floor although specular should be 0%, but its reflecting - is it reflecting diffuse component? I am not a expert in this polarization stuff.
Also for your normal map creation from 4 angles lighting setup, how can I do it? Say I want to create normal map of my rattan chair and take 4 photos, what next?
Thanks.
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According to this, viewing the picture with the fur, in the first picture, there is a visible reflection on the floor although specular should be 0%, but its reflecting - is it reflecting diffuse component?
The fur is lying on my glass sofa table.
Also for your normal map creation from 4 angles lighting setup, how can I do it? Say I want to create normal map of my rattan chair and take 4 photos, what next?
You want a really bright and large surface light.
Something like this (Picture from Wojciech Piwowarczyk, he did some kickass leaves textures)
(http://i.imgur.com/9ApwEIR.jpg)
After that, head over to http://www.zarria.net/nrmphoto/nrmphoto.html
EDIT:
I want to add that I don't use this method anymore. After I discontinued my scanner box I changed over to photogrammetry.
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I saw someone on History Channel used this program in a Tomb in Egypt.
http://www.hpl.hp.com/research/ptm
You can use one/two snooker balls or place your flash in fixed positions.
The guys on History Channel took pictures in an umbrella pattern on two axis.
I did a quick test in Corona. I placed my snooker ball in the center to make my life easier. I only did 15 renders, from what I have read you want 32+.
(http://i.imgur.com/COH4mPA.jpg)
Here is the result from only 15 badly placed lights.
I need to go and buy some snooker balls, this could be great for fabrics and other small details.
You only need a snooker ball, flash and camera.
(http://i.imgur.com/alorJJB.jpg)
(http://i.imgur.com/K2ZIPcz.jpg)
(http://i.imgur.com/2a50HmI.jpg)
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Why do you need a snooker ball? Does software calculates light positions from highlights on that ball?
Quality of resulting map is truly impressive, but boy... that really comes at the cost :/
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Why do you need a snooker ball? Does software calculates light positions from highlights on that ball?
Yes. You place a point on the ball, adjust the radius and then click Calculate Position. They recommend two balls for best results.
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I want to add that I don't use this method anymore. After I discontinued my scanner box I changed over to photogrammetry.
Can you elaborate ?
I started to build the scanner, and my brother is doing the software part, I pretty much want the megascans 'ghetto' version. Is this something you moved away from ?
I need it only for micro-detail (fabrics), where I am afraid photogrammetry would simply suck, together with much harder shadow removal.
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I wasn't 100% pleased with the normal maps, and it was really hard to get both albedo and specular without a Fast Polarization Modulator.
Micro-detail was the first thing I thought about when I saw this on History Channel. They could see crazy details on the Egyptian/Greek artifacts. Cops used this method to see old handwriting that was indented in paper.
I will mount 4/8 lights inside the box and use the "fixed position" method. Fast Polarization Modulator is out of my price range, so I will have to do with only albedo.
It's time to convert the ghetto box into the sexy box!
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But was the issue in the nature of the setup or just the way you had it ?
I want to build this in studio room, fixed, nothing portable. So the flash lighting would be of presumably good quality, and imagery will be taken with Nikon D800.
What makes the Modulator superior ? ( overall and for speculars)
The method above would need fixing the bellow ball part for nicely tiled texture, and I would like something more automatic. Or would you just place the ball(s) elsewhere than middle ?
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I want to build this in studio room, fixed, nothing portable.
That changes everything. You only need a modulator if it's portable.
You have to rotate the filter on the camera 90 degree, and this is really hard to do on the portable version, since it's inside a box. With a modulator you just hit the on/off switch.
For your stationary build I would recommend getting some linear polarization sheets, don't even bother with circular polarizers. You take the first picture, turn the circular polarizer on your camera, and everything is unaligned. Just a little wind breeze is enough to ruin the 100% specular picture. You have to use manual focus too, and the circular polarizers messes everything up when you turn them, damn circular polarizers.
But was the issue in the nature of the setup or just the way you had it ?
It was because I used the other normalmap method where you take a picture from each side.
The method above would need fixing the bellow ball part for nicely tiled texture.
The ball is only needed if you don't have any fixed lights, so you can calculate the position based on the highlight.
Since the lights will be fixed on the rig, I only have to tell the program where the lights are (x,y,z). This is done with a .txt file.
I guess you want to build something like this and just turn the ceiling lights off.
(http://i.imgur.com/6GnHhdS.jpg)
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Yeah, I want pretty much replica of that :- ).
But you got me intrigued with the specular addition.
Do you have any idea/guess how do the Quixel guys process their roughness maps (from what?) ?
One last question, bit of topic, but touching tangentially to what is on first page, does from your observance Corona desaturate Albedo with specular correctly to real-life ? I guess it does, just wondering, since when I needed to use lower specularity for fabrics of low glossiness, I had to likewise desaturate the diffuse otherwise it would saturate too much at angles that otherwise wouldn't. Since the glossiness curve will be remapped, this won't be an issue anymore soon, but is the specular overlayed in way that we can really use the correctly saturated captured albedo in diffuse slot ?
The textures I see in PBR game papers, I always brighter and saturated that even I use, and I think I kind of try to match them well (although still by eye....).
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I read somewhere that people are generating roughness maps based on pixel intensity from light sources. I bet it's something like that.
They kinda look like 100% specular pictures, the concrete maps have small white stones here and there.
All the Quixel maps are Highpassed with 256px, that's why all the maps are 127 RGB.
EDIT to your edit :P:
I can take some albedo/spec pictures tomorrow and compare.
I want to analyze the new "The Reflector" OSL shader from Rens too.
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That does sound plausible, at least for non-metals.
Does his shader work under Corona too ? (well since OSL is universal, though I didn't follow if Corona allows it). You want to test his fake rough fresnel :- ) ?
Btw, saw this super toy at EUE from one guy, could replace your mirror ball :- ) https://theta360.com/en/ I for sure am getting one soon.
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You want to test his fake rough fresnel :- ) ?
Yes :P It looks like the sexy PBR shader Blender people use. I need to do the tests in Mr. V :(
Hm, Theta was affordable too.
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Lots of useful information, my passport is on its ways so will be able to make my own tests :)
I also ordered these chrome balls http://www.ebay.co.uk/itm/3-Size-Stainless-Steel-Mirror-Sphere-Hollow-Ball-Home-Garden-Ornament-Decoration/221801673314?_trksid=p2054502.c100229.m3211&_trkparms=aid%3D111001%26algo%3DREC.SEED%26ao%3D1%26asc%3D37319%26meid%3Dcbb625eecb8a42bba8432b13f0ec23c4%26pid%3D100229%26rk%3D1%26rkt%3D8%26sd%3D221801673314.
Lets see how they come up, its 18cm diameter for 6 euros :D
Snooker ball method seems okay, but more elaborate than 4 angles flash, comparison would be awesome.
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Looks like some fun content is coming! Can't wait to see some examples and try some ideas myself.
I still have some huge bearing balls (https://www.google.pl/search?q=bearing+balls&biw=2560&bih=1317&source=lnms&tbm=isch&sa=X&ved=0ahUKEwib8cv1lL7NAhVFDZoKHWB2CXUQ_AUIBigB) somewhere, so I might try with those, or use something else...
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Looks like some fun content is coming! Can't wait to see some examples and try some ideas myself.
I still have some huge bearing balls (https://www.google.pl/search?q=bearing+balls&biw=2560&bih=1317&source=lnms&tbm=isch&sa=X&ved=0ahUKEwib8cv1lL7NAhVFDZoKHWB2CXUQ_AUIBigB) somewhere, so I might try with those, or use something else...
and how, we have waited?