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genesis1
10-14-2015, 02:22 PM
Sometime back I saw a tut somewhere about how to make something like a martian rover follow a terrain and also leave tire tracks on the surface. If anyone can point me in the direction of a tut on how to do this I would be greatful. :)

vonpietro
10-14-2015, 04:21 PM
content from 2015 has a rover =)

it doesn't do the tire tracks, but I believe you can do this a number of ways.
1) texture reveal - for simple textured tire tracks. (a cheat really)

2) object reveal through a morph (plus texture to darken alittle)-
build an floor object with tracks, flatten in with a morph.
You would then use the normal displacement and choose morph instead of normals. amplitude will set how much morph, select the morph map.
then you wold use gradient map with distance to object
set your alpha to 0 - or whatever suits you it will control the height of the morph. - one point on gradient needs to be 0 0 , and the other 100 100 - set a distance that works for you.
the problem with this technique is persistence - because there is a fall off with the null, you can't make the tracks stay unless you stop moving the null.
you can use multiple nulls in the gradient - by making layers, but they will be additive if they cross over each other so you have to move them carefully so they dont overlap.

hmm, only problem is I'm not seeing what controls the falloff for the null area. (how much area the null influences - except the obvious proximity)
You can probably use an animated weight map thats controlled by one null to reveal as a better effect i think
but i have not set that up, so i'm not sure how that would work.

3) 2015 - you could use an object to add lines to the floor - the object would be a track shape, so the lines would be a track shape when they intersect - the benefit is it would not matter if you had bumpy surface !!
and you can litterally just lower them into place one by one, or have them lower in a sequence controlled by the movement of the object. - neato 2015 cel edges I love that new feature. The track shapes would of course be hidden by radiosity and camera and turn off cast shadows for them too.

there are other ways still too -

MonroePoteet
10-14-2015, 04:48 PM
There's a portion of the SigGraph 2013 introduction to the RayCast Geometry node which is about a car on a surface:

https://www.youtube.com/watch?v=TKWTk5VYNZk

The car-on-surface part starts at about 10:56. If the surface is rough, you'll probably want the RayCast Node on the Goal object for an IK bone chain for each independent suspension wheel.

To reveal the tracks, I'd use the RMan collection Marker Pen to set the flat sand surface to transparent with the tracks modeled underneath:

http://dpont.pagesperso-orange.fr/plugins/Textures.htm

mTp

djwaterman
10-14-2015, 04:56 PM
That's a cool solution, to reveal a pre-modeled track. Here's a link to a tutorial for making footprints using cloth effects that might also help.

http://forums.newtek.com/showthread.php?77078-Creating-Foot-prints-in-the-ground-using-Cloth-FX

MonroePoteet
10-14-2015, 05:00 PM
BTW, here's a sample scene based upon the SigGraph presentation. A key element is the ConvertHitNormal2HPB node, which sets the appropriate Heading, Pitch and Bank on the car based upon the RayCast's normal with the surface.

mTp

vonpietro
10-14-2015, 11:13 PM
YOU CAN also do the clip map reveal - with a second identical geometry but with tracks, and wipe it on, revealing the tracked object via the clipmap tied to a null.

genesis1
10-15-2015, 04:35 AM
Thanks to everyone....lots of info there for me to look at. Will see if I can get it to work and post an animation when completed. :)

genesis1
10-15-2015, 11:47 AM
BTW, here's a sample scene based upon the SigGraph presentation. A key element is the ConvertHitNormal2HPB node, which sets the appropriate Heading, Pitch and Bank on the car based upon the RayCast's normal with the surface.

mTp

I'm probably missing something obvious here...but where do I find the ' ConvertHitNormal2HPB node' ?? btw there's no mini car in the zip file just 2 terrains :)

MonroePoteet
10-15-2015, 12:10 PM
I'm probably missing something obvious here...but where do I find the ' ConvertHitNormal2HPB node' ?? btw there's no mini car in the zip file just 2 terrains :)

RE: ConvertHitNormal2HBP, it's in the LW 11.6 Content folder: Content=>Nodes=>RayCastAssist=>RayCast-NodalMotion

RE: the scene file, very strange. I downloaded the ZIP, but I see 2 Minicars rather than 2 Terrains. It appears that somehow it got corrupted when I packaged it for upload, probably user error. Here's a corrected ZIP file.

mTp

genesis1
10-15-2015, 12:17 PM
RE: ConvertHitNormal2HBP, it's in the LW 11.6 Content folder: Content=>Nodes=>RayCastAssist=>RayCast-NodalMotion

RE: the scene file, very strange. I downloaded the ZIP, but I see 2 Minicars rather than 2 Terrains. It appears that somehow it got corrupted when I packaged it for upload, probably user error. Here's a corrected ZIP file.

mTp

Thanks for that! :)