3D Volume Rendering using Raymarching Demo

Volumetric Texture version here
https://github.com/brianasu/unity-ray-marching/tree/volumetric-textures

https://github.com/brianasu/unity-ray-marching

Source code now available. Requires Unity pro 4.5.0 enjoy. I'll be updating it when I more free time.


Ray marching in Unity3D. All the 3D is done by marching through a 3D texture. The only geometry used is a cube.
Needs a decent shader 3.0+ card.

Only works on webplayer 3.4

Hold down right mouse button to rotate the cube.

Web player Demo
http://dl.dropbox.com/u/17249329/raymarching/WebPlayer/WebPlayer.html

Can read more about it here
http://graphicsrunner.blogspot.com/2009/01/volume-rendering-101.html

 

Doesn't seem to work.. my system def. meets requirements.

Win7 / 64 bit

 

I just get a black screen, but am using 3.5 test player, so that might be it. Have you tried the 3.5 player? If it doesn't work for you in the test player could you submit a bug report so they know about it?

 

Yup 3.5 webplayer doesnt work. Only 3.4

 

Seems to render fine at my end (webplayer 3.4) . Is there a way to change the resolution/granularity of the intervals? I understand that we may need to recompute if we make such a change.

I could suggest :
1) please change the background from black to something lighter? It took sometime to figure out that the "Alpha Strength" "Scroll Speed" are sliders
2) If you could add an fps counter.
3) Allow the webplayer to go full screen.

It's a cool tech demo but off the top of my head with this kind of massive fill rate hits, its only practical in small demos. Even Kyle Hayward's original demo runs at 27 fps on my GTX 260

 

Thanks for the suggestions.

Yeah you are right fill rate is a problem but if you are using it for soft particles like clouds you can probably do a low res off screen render then upsample.

To change the intervals you'd have to recompute the 3D noise each time plus I would have to adjust the amount of steps the ray marcher takes. This might be hard because loops have to be a constant number.

Kyle Hayward's is probably more computational complex because he uses a larger number of samples and uses transfer functions.

 

really cooly, would love to see some code, or more explanation

 

Man...i really wanna see it, but i got black screen too. Can you post some pic?

 

I love the demo, you say that all 3d is done in a 3d texture. As unity does not support 3d textures how do you pull this off. I am assuming that you are using a 2d texture as 3d? Or is there a better way? Can you give code examples?

 

Images/video?

 

Nice

 

Yeah Unity doesn't support tex3d. (Unity 4 does) I just simulate it by laying out my 3D texture in a grid. Then I just look up the uv coordinates from the 2D grid. The only problem is that you don't get any bilinear filtering in the "z" direction so you have to do that manually by taking the neighboring slices and blending them. It's probably better to wait for Unity 4 to get a proper tex3D which probably much faster to do.

 

That looks really damn good.

 

Medical Visualization with volume rendering.




​

 

Hey jcongote!! Have you used a 3D Texture to do that? That's awesome!! And how did you use the MRI images to create the 3D texture?

Thank you!!

 

Hello Txasti, I didn't use any 3D texture... I just make a 2D atlas, you can check more information in this link:

http://cdn.intechopen.com/pdfs/34474/InTech-Volume_ray_casting_in_webgl.pdf

Bye

 

Hello again jcongote!! Your paper is impressive!! But you have developed it for WebGL. How did you developed it in Unity? What I mean: What do I need to create something similar?

Thank you again and thank you for your quick response!

 

Hello Txasti,

I apply the shader to a cube, and use shaderlab with GLSL language, and then some small fixes. There is a lot of improvements which can be done.

 

Hello jcongote!

Is it possible to test that shader? It would be great! I have experience in unity so I could try to improve your code, and of course I would share with you my contributions.

Thank you in advance!

 

brianasu great job, is there any chance of releasing/providing the demo project?

 

Yeah sure. Let me just clean up the code a bit So i'm not too embarrassed to release it to the public.

 

Hey, I used your ray marching technique to visualize my sound wave field. Here's a video:

 

+1 Love that!

 

Ok that's cool!

 

Here's another video, showing off dynamic emitters. I'm making this game for the oculus/indiecade vrjam. Before ray marching, I used some crappy procedural geometry (actually it was pretty cool using compute buffers and drawindirect, but it didn't look nearly as good as this).

I'm really glad you guys think this is cool.

 

Wow really nice Have you solved the camera intersecting the volume? I think you have to render a reverse geometry to get a proper depth buffer.

 

Hi,

So ? any progress on a public release ?

 

any chance of an asset store release?

 

I'm actually redoing the code now. I'll release for free in a week or so.

 

Woot ! \o/

 

https://github.com/brianasu/unity-ray-marching

Source code now available. Requires Unity pro 4.5.0 enjoy. I'll be updating it when I more free time.

 

Heya,

looks very promising, although I only get a pink screen in the demo scene - but no errors at all. What could I do?

 

It might be a Mac / PC thing again. Usually happens. What kind of system do you have? I'll double check it on my win machine. I usually develop on mac.

 

Yeah I'm also getting some win/mac lineending warnings - so that could have to do something with it, indeed. I'm using win7, 64bit.. supporting DX11 and all, but not working yet, all my mat's seem to stay pink.

Thanks for the quick response, I'll definately follow this thread.. volumes are such a nice feature.

 

Yup it was some silly errors in my code. Should be working on windows now just pull for Git hub again.

 

Nice, thanks, works now! Time to dig deeper to get the repetive pattern smoothened when looking from the wrong side.. to get an actual cloudy look. But that is definately more than I was able to come up with ^^

 

Thanks. From what I read you can sample a noise texture to jitter your viewray so it reduces the repetition. Another options is to increase the number of slices. I might try these options to see if they look smoother.

 

How can I change the code to render my Texture3D? For a given Texture3D, how can I show it using your system?

 

Hi it seems everyone wants this so I've uploaded a new branch that renders a volume using textures

https://github.com/brianasu/unity-ray-marching/tree/volumetric-textures

 

Are 3D textures completely a Unity Pro feature, or your code requires some Pro features to be used?

 

For Unity 4 it's pro only but Unity 5 personal should have everything you need to run it.

 

brianasu, I download your latest volume render sample, I find the memory cost is very large in the "volumeColors = newColor[x*y*z];"，if I set the x*y*z to 512*512*512, the editor will be error of out of memory ,so, could you tell me how I reduce the memory usage? Thank you!

 

512x512x512 means you are basically using 512, 512x512 textures. The array is going to be huge. The easiest solution is just to reduce the size.

A more complicated solution is to break down the volume into multiple chunks like 4 256x256x256 chunks. So you only need to allocate a subset of color array and reuse it.

I didn't implement this because it would require me to have a method to render multiple volumes and sort them

 

Thanks for your reply! I think the complicated is how to break down the volume and reconstruct it, and the shader will be added more？

 

I find a small bug, the MRI tif flies No.99 seemed to be put into the No.1 position of the volume, but I don't know why, I check the code there seemed no any mistakes.

 

It probably require doing something like this

http://graphicsrunner.blogspot.com.au/2009/02/volume-rendering-201-optimizations.html

Ok thanks I'll take a look at that.


Also you could possibly generate the volume textures offline first and then load them in. The final input is a 3D texture but it does not need to be constructed run-time.

 

hi, how do we change the color/material in the master branch? Also, if i have external voxel data, basically i have to modify GenerateNoise function to load my data?

also,
@brianasu I am interested in your V-Fog volumetric fog shapes, wondering if it is extensible to procedurally generated artbitrary shape mesh?

 

Yes you would have to modify the code. The volumetric texture one is better since you can just generate the textures outside then pass them into the system.

V-Fog only works with convex shapes now because I haven't handled any of the complex multiple in-out scattering of concave shapes. I'll probably support 3d textures now since unity has updated that so you couldn't technically create a 3d texture and use that as a shape.

If you email me at brianvlights@gmail.com I can email you a demo copy.

 

Hi,Brianasu
I download your volume rendering demo, but I found when I change only one dimension scale of xyz of the cube(I try to adjust the scale of the MRI head) and very close to the camera, for example, I change the z scale to 5, x and y is 1, then as a result, the
head will be shown as multi-copy head like when it is rotated in some angle, you can see the screenshot below, but when the xyz scale to the same size will not happen.
So, could you tell me why this will happen and how to fix it?

 

This is caused by unity baking the scaling of the mesh. This messes up the local vertex coordinates.