Dusty Car

[cherm]

hi there,

I am struggling to get particles to form the shape of my car model. I tried rendering out with sprites, but it didn't have the exact shape of the car. Also, I rendered out with VEX MetaCloud, and it came out even worse. Then, I tried to all the particles as very tiny spheres, like 0.004.

This is rendered with Sprites

rendered with small small spheres in the Render Tab in Particle SOP.

rendered with VEX MetaCloud

This is the shape of my car model that I am after

The look that I am aiming for is a car covered with dust, which is very similar to the references below.

Thanks in advance for your help

Cherm

Edited May 16, 2007 by cherm

[GallenWolf]

Hey man, do you need to blow the dust off or something like that? If all you are looking for is just a dusty static car perhaps you could do it all via texturing?

if I need it to blow off perhaps I'd try like tons of particles with a thin width attribute.

Alvin

[altbighead]

try scatter sop to get tighter resolution across the car geometry?

no POP expert here !

[sibarrick]

I reckon you are getting a very similar level of detail with your first sprite effort, the problem is that a car is less recognisable than a face when you remove all the detail. The thing that makes the face read as a face is the eyes and mouth. Its a well known psychological effect that people will see faces in anything that vaguely has 2 circles for eyes and one for a mouth. I don't think the same can be said for cars.

Maybe you can push the contrast in the dust colour around areas like the windscreen to make it more defined and use some smaller higher density particles in areas like the wing mirrors to try and get more definition in some small parts. I expect the wheels are quite important in what makes a shape read as a car too.

[cherm]

Hey man, do you need to blow the dust off or something like that? If all you are looking for is just a dusty static car perhaps you could do it all via texturing?

if I need it to blow off perhaps I'd try like tons of particles with a thin width attribute.

Alvin

Thanks Alvin for your input. I am quite new to Houdini.

What do you mean by "thin width attribute? Do you mean to reduce the sprite scale down right?

cheers

cherm

I reckon you are getting a very similar level of detail with your first sprite effort, the problem is that a car is less recognisable than a face when you remove all the detail. The thing that makes the face read as a face is the eyes and mouth. Its a well known psychological effect that people will see faces in anything that vaguely has 2 circles for eyes and one for a mouth. I don't think the same can be said for cars.

Maybe you can push the contrast in the dust colour around areas like the windscreen to make it more defined and use some smaller higher density particles in areas like the wing mirrors to try and get more definition in some small parts. I expect the wheels are quite important in what makes a shape read as a car too.

Thanks for the reply.

So you think I need to emit particles seperately? There is no possible way to do it in one go right?

cheers

cherm

[MIguel P]

So you think I need to emit particles seperately? There is no possible way to do it in one go right?

cheers

cherm

You can paint an attribute on the car surface and then use it to control the point density. Are you using POPs? I would do this with the scatter SOP and randomizing the point position.

[ygalula]

Perhaps what is missing in the VEX MetaCloud image is self-shadows.

[cherm]

Perhaps what is missing in the VEX MetaCloud image is self-shadows.

well, I did apply the ray shadow in it.

[steven]

This will come down to lighting and coloring, I think. Getting an accurate shape and acceptable particle performance is about as good as you can expect. If you're looking to keep the hood lines and front grill of this car, you should start thinking about colors choices and the compositing stage.

Edited May 17, 2007 by steven

[cherm]

This is what I have for today. I tried to paint my car for a specific part to scatter more points, but it's still not the best look. I still have to keep trying. I might have to create different sets of particles and comp them together. Now I will start to animate my car first and then see how it goes with particles on it.

need more advices

cheers

cherm

[steve-o]

hey try this,

I worked on this for a friend.... i would suggest making a vex shader and put your location pops in specific places where you want great amount of detail

steve-o

particleface.hip

[cherm]

hey try this,

I worked on this for a friend.... i would suggest making a vex shader and put your location pops in specific places where you want great amount of detail

steve-o

thanks steve-o

i will soon post my final work after finished.

[Daniel]

I think the main thing that will give you detail is shading normals.. there are several ways to get the car normals into the point cloud and that will give you a lot of the visual cues of the car contours.

The scatter sop should contain the surface normals (if they were defined before scattering).. so from there it should be a matter of adjusting the shader code to respect the normals. This would give you a normal for every seed point .. you could get fancier and stuff that scattered points into a point cloud that's accessible at render time to query the normal at each shading sample for more accuracy. That may not be needed depending on what look your going for.

d

[cherm]

hi all,

http://www.divshare.com/download/963660-b30

here is the link you all can download to see my final piece. all 3D is done in Houdini. composite is done in Shake.

cherm

[Alexander Weide]

looks very good, the only thing is, the dust behind the car, i think its the dusty wich swirls off by cars motion, that dust is to heavy, so its not easy to see the car. But thats my opinion, i hope i can create my vfx what i wanna do............iam maya user for years, sometimes i think........."use blascode and not houdini"))

[cherm]

looks very good, the only thing is, the dust behind the car, i think its the dusty wich swirls off by cars motion, that dust is to heavy, so its not easy to see the car. But thats my opinion, i hope i can create my vfx what i wanna do............iam maya user for years, sometimes i think........."use blascode and not houdini"))

really do appreciate your opinion. well, my intention for this project is to have the contrails and the 'dust car' are blended together as if they are parts of each other. the below is one of my references. However, you might be right. it might look better if i make them look seperate so the car can be more obvious.

[Alexander Weide]

ok if you want that you finished well. it looks very good, i wish i can do that stuff.......

[cherm]

Thanks! I will also try to do as you suggested if i have time.

[edward]

Just an idea, what about cheating by taking a non-smoke rendered sequence and subtly compositing it on top of the smoke sequence?

[cherm]

thanks for the idea.