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.
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?
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.
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.
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.
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.
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 :]
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.
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
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.
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.
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
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.
Yes, except I don’t have to travel to Pakistan and drive into the desert at night
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
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:
You move your light source around the room and take multiple pictures. You will get better result the more pictures you take.
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)
