A simple question but new to Blender and need help ASAP!

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1

Hello Blender artists!
I’m new to Blender and using it for 3D rendering of the human brain for a scientific publication (to be submitted on Thursday!!!)

I have 56 separate meshes (generated from separate sections of the human brain, which all fit together to form the whole brain).

I need to color each mesh (separate brain sections) a different color (this I know how to do… at least one-by-one as I load the meshes).

Now here are my problems…

#1 I need to specify precise colors ON A GRADIENT for my 56 meshes… I want the first mesh to be light gray, and the last mesh to be dark blue, and I want all meshes in between to transition in a evenly manner from light gray to dark blue. I know I need to specify exact RGB values, but it’s more complicated then using evenly spaced values from one slider alone, because all three color parameters (R,G, and B) and needed to create these colors.

#2 I would like to be able to view a list of all the meshes I have, and to go down that list and color my separate meshes, one by one. It’s difficult to find the meshes once I’ve loaded them, because they all interlock in 3D space (the brain is complicated, after all!) So far, I’ve only been able to select colors for meshes as I load each mesh in turn, using the materials buttons.

#3 I would like to render the whole brain looking from the side (which I can do), but I would also like to render the brain, cut in half down the middle (so that the different sections down the middle of the half brain are exposed). I can do this by moving the camera inside the brain, but then everything is too close up. Is there a way I can make half the brain transparent or another technique so that the other half can be seen?

#4 Finally, I’ve been told that radiosity rendering is the way to go for a natural effect. How specifically do I accomplish this (remember, I’m one step below amateur!)… something about using an icosphere with its vertices as an emitter as in the skydome example??? Or something else maybe???

I would much appreciate help on any of these problems.
Thanks!

2

#1 - maybe there’s a way to write a short python script that will dump the color values, or a website that will list gradient points for you.

#2 - That’s what the outliner’s for. Reasonably named objects might not be included, but here’s the general idea. To make new windows, right-click on a line between windows or a screen edge perpindicular to the ‘cut’ you want to make in a current window. You can drage the ‘cutter’ thing anywhere once you start.
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#3 - Transparent could be cool but could also take a huge render time and a long time to set up because it’s a materials thing. If your objects are set up so that the brain is in halves already you can just move some to a different layer (M-key) and turn that off for some renders. If not, well, meshes are hollow so arbitrary curts require surface reconstruction. Not hard, but can be tedious and confusing if you haven’t done much blender.

#4 Radiosity is good for things that glow and for when you really need to bounce light off of objects. For showing crannies and crenulations, Ambient Occlusion is what you probably want – it shades things based on how many light rays can get how far away from a point, so secluded areas get the least shading. Can take forever but the 2.46-almost versions have adaptive and fake versions that are faster.

3

I’m a total nub… but would layers help this? Putting the various meshes on different layers and turning on only the ones you want to render?

4

Thanks guys,

As far as rendering only half the brain, unfortunately, the meshes for the brain sections do not split down the middle, so I need to somehow lop off one half of the brain so that the other side is visible (the meshes go across the midline of the brain, so the meshes would be cut in half, for the most part.)

I’ll check out Outliner and Ambient Occlusion, thanks

5

Hm … that’s gonna be tricky. Booleans tend to leave crappy polygons but if you’re doing nothing else with it it might be tolerable.
Booleans only work on two meshes at a time, so what you would probably want to do is make a seperate file / scene-with-local-obdata, join the meshes into 4 compound meshes (since you cano only have 16 unique material slots per mesh), and cut each oft those against a large box conatining the part of the brain you don’t want.

6

So your questions aren’t very simple - when it is about working on a big nubmer of objects. It is always good to support your questions with images if possible.
There are two ways to do #1, that I can figure out:

  1. To create separate materials with the desired color
  2. To create a texture containing all colors from the gradient.
    Material creation: The gradient itself can be created simply by animating the RGB value within 56 frames starting with the first color (light gray) and ending with the second color (dark blue). Extracting of every material can be done by scripting or by hand. Unfortunately I don’t know python but I am sure that it could be done. I created the materials manually and it took me about half an hour.
    Texture creation: It is simple, create a texture with all gradient colors in it (either by stitching rendered jpg files for every frame, or by genereating the colors in external 2D program.) Then arrange the all 56 objects using the texture as reference so that you can map them from a single view. Texturing the objects with solid colors probably is even qucker than material creation.
    Ofcourse that is the basic idea.

According to “ASAP” in your topic, I am late with the answer, but it is good to know.

that but it needs half an hour of your time anyway.

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