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Scattering - Decimating a point cloud with another scatterer

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Scattering - Decimating a point cloud with another scatterer

Unread postby witheredhack » Tue Jun 09, 2020 12:10 pm

Hi all,

I am after some help with scattering.
I am building an environment which will have at least three scatterers in different areas of the terrain.

1 - forest trees,
2 - smaller swampy shrubs
3 - mainly rocks,

Each will have their own masks that drive the point clouds through the decimation input.
These masks overlap each other where the terrain transition from one to the other.

I am wondering, for example, how I would set it up so that the result of the first forest tree scatterer holds out the second smaller swampy shrub point cloud/scatterer so I don't have intersecting geos, but can still have the transition areas.

I was trying to do something with the decimate value of the swampy scatterer, but couldn't get that to work out. Also getting a little confused between decimating the point cloud and decimating the scatter.

Any tips or advice greatly appreciated.

Thanks
witheredhack
 
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Re: Scattering - Decimating a point cloud with another scatt

Unread postby dboude » Tue Jun 09, 2020 1:19 pm

Hi,

Decimating the point cloud deletes points when decimating the instances from a scatterer removes just the instances but keeps the points (that can be used for another scatterer). In your scenario, I would use just one scatterer and drive the distribution with scatter input mode set to "ID". Several objects can have the same ID so, with masks, you can define areas in where some objects are scattered but not the others.

Here is an example of what I'm saying.

Scatterer_Input_Driven.project
(45.35 KiB) Downloaded 68 times


Cheers ;)
Démian
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Re: Scattering - Decimating a point cloud with another scatt

Unread postby witheredhack » Wed Jun 10, 2020 1:09 am

Thanks Demian, I'll give it a try and let you know how it goes!
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Re: Scattering - Decimating a point cloud with another scatt

Unread postby witheredhack » Wed Jun 10, 2020 5:14 am

Hi thanks for your reply and for the example project.

Am I correct in saying it is the value of the colour coming into the scatter input drive the ID.
In your example:
0-1 gives you box ID 0
1-2 give you sphere ID 1
2 or above gives you cylinder ID 2

1) If I have multiple image maps/masks that have values 0 to 1, how do I drive then combine them to drive the scatterer. Do I need to texture rescale these so they have different values, 0-1, 1-2, 2-3 etc.

2) how do I have blank areas where nothing is scattered. I.e. values of 0 in my original masks.

Thanks again
witheredhack
 
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Re: Scattering - Decimating a point cloud with another scatt

Unread postby dboude » Wed Jun 10, 2020 12:55 pm

Hi,

Yes, you have to rescale the values to fit the range of your ID's.

To have blanc areas just input a value that is not corresponding to any ID.

Cheers
Démian
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