EDIT: I posted this on CG Cookie community and found a very easy solution. Visit here: http://community.cgcookie.com/t/how-can-i-animate-a-smooth-cross-sectional-view/5082/14
This is my first ever animation and I encountered difficulty animating a cross-section/cutoff in an assembly consisting of multiple parts. The aim is to gradually fade half of the assembly to reveal the internal structure of the product, and although I have achieved that effect, the setup and animation took a long time (plus the final result is very choppy/unsmooth).
To get a better idea of my problem, please check out the video i posted (fade sequence at 00:29 to 00:36):
Having searched online for a solution, my approach to create a cross-section was:
- Duplicate my assembly and move to another layer.
- Boolean (difference) operation to cut the duplicated assembly into half.
- Move the cut assembly back to the original layer (so now the two assemblies have the same coordinates)
- Fade-out the untouched assembly to reveal the cut assembly (fade controlled by shader transparency).
My sectioned assembly was transparent at the beginning of the animation (I thought this might help to lower rendering times)
So as the untouched assembly fades-out, the sectioned layer fades-in (and vise-versa). See dope sheet attached (green line is the point where the assembly starts to fade-out).
So my question is, am I doing this right? What is the best way to animate a seamless cross-section?
I’ve been using Blender for only 4-months and I consider myself to be a CAD engineer and less of an animator, so any help and criticism would be very much appreciated :).
Can you post a render, or video, or upload a .blend, or something? From the Outliner screenshot you sent, all I can tell is that you added a bunch of keyframes, but I don’t know what those keyframes are for.
The trick with cross-sections, in my experience, is that we look at our full model and imagine it as a solid object, so when we cut it in half, we are perhaps surprised to see that it isn’t as clean as we thought it would be (as I’m sure you’ve noticed). Rather, the cross-section part needs to be modeled along with everything else. So a boolean approach sounds like a potentially problematic approach, but hey – if it’s working…
That said, post a .blend, and we can see what you’re talking about. Even a limited version of your project would be helpful.
Hi, thanks for your help :), a video was already uploaded to Youtube and a link was provided. I will upload the .blend file as soon as I can.
From the Outliner screenshot you sent, all I can tell is that you added a bunch of keyframes, but I don’t know what those keyframes are for.
Apologies, I have updated the dope sheet IMG with labels to give you a better idea of what the keyframe are. Basically:
-The yellow box highlights the full assembly which is fully visible from the beginning of the animation. This full assembly starts to slowly fade-out beginning at frame 749-765. This is fade is reversed at 847-864.
-The blue box highlights the sectioned assembly which fades into the scene beginning from frame 753-754. This section stays visible until 857-858.
The trick with cross-sections, in my experience, is that we look at our full model and imagine it as a solid object, so when we cut it in half, we are perhaps surprised to see that it isn’t as clean as we thought it would be (as I’m sure you’ve noticed). Rather, the cross-section part needs to be modeled along with everything else.
I don’t quite understand what you mean by ‘we look at our full model and imagine it as a solid object’. The objects are (mostly) solids.
Each component in the assembly was manually sectioned using boolean (and yes, the operation was tedious and counter intuitive, but the final result was quite clean).
So to summarise, is there a way to section a assembly (other than boolean) and then animate the cross-sectioned part seamlessly.