My scene has a large number of low poly trees, and I am using the Multi-Sub Map to get more variation in the foliage.  I’ve set it to do a Random placement of the 4 maps, as they are all instanced mr proxy objects that are xreff’ed into the scene.

In one shot, I am rendering the same camera sequence 4 times, each time turning on another layer of geometry.  I will be fading from one sequence to the other, so the new geometry fades in with the camera motion remaining smooth.  However, I’ve discovered a problem…

Each of the four passes has different maps assigned to the trees, so the foliage switches from one pass to the next.  The only thing that is really changing in the scene is an additional layer is made visible.

Does anyone know how and/or when the IDs are generated for the Multi-Sub Map?  I’d like to understand HOW this works a little more before I use it more.  If I would need to replace a few frames from an animation, I want to know I can render them using the same trees each time.

Thanks.

3DS Max Design 2011 64-bit - Advantage Pack
Dell Precision T5500, Dual Six Core Xeon X5650 @ 2.67GHz, nVidia Quadro 5000, 24 GB RAM, Win 7 Enterprise 64-bit
Minneapolis, MN, USA

I’m not sure what is causing the problem, I have recently done a project using a similar technique, I used loads of mr proxies for cars trees and people and used multi sub maps in the materials on all to randomize the colours.
Yes, it’s one of those annoying “I don’t get that problem” replies.
The random colours assigned stayed put, at least when no more copies were made.
For example, I have a number of cars in the carpark, they will render on multiple cameras, on the farm with multiple nodes, and the colours stay the same. But, if I decide I want more cars and make more copies, the colours get a re-shuffle.
The only thing I can think that you are doing differently to me is using proxies in Xrefs.

Never tried it with Xreff’s and Proxy objects but if the multi-sub map is assigned on all the objects first, the randomizing remains the same and don’t change when you hide some of the object and render new image. The IDs are generated once, when you put the material on the objects.

ivan

I’ve just been doing some tests on this to see if I can fugure out how it works.
It seems Chris that you are right about hiding layers, and I was wrong about creating more copies.
I created a scene with a ground plane on the default layer, I then added an mr proxy and loaded a car model to it. I applied a material to the proxy which has a multi sub map to randomize the paint colour of the car. I made a few copies of the proxy and pu them on a new layer.
They render with varying paint as expected.
But then I hide the default layer, which has only the ground plane and skylight on it, the cars have changed colour.
Unhiding the default layer brings them back as they were.
I copy the proxies to make another row of cars and put them on another new layer. In the render the origial row of cars still have the same colour.
If I hide the first row of cars, the second row render different colours to how they did last time.
I copied a third row of cars and put on a new layer, and the one before keep their colours and the new ones have their new colours.
But if I hide the middle row, the third row takes on the colours of the middle row.

It seems to me that the colours are assigned by the object’s ID number in the scene (in their order of creation), but as objects on layers are hidden, they are skipped and the next random colour is given to the next visible object.

So I don’t noew think it’s an Xref thing at all. But it may be a proxy thing, I’ve not yet tested with non-proxy objects. Or it could be a layer thing, I’ve not yet tested with hiding objects per object rather than by layer.

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A bad news guys, the randomizing is renewed after hiding objects. (See Attachments)
Sorry to having mislead you; this diminish the power of the tool a bit
but nobody is perfect what can we do. :)
Maybe we could get something trough the wish list.

ivan

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Thanks for looking into this guys.  Seems like the “random” feature isn’t as good as I once thought.  Maybe I need to find a way to randomly assign Object IDs to a group of objects.  I’ll bet there is a script out there somewhere.  Then I can set the MSMap to use that instead, and it won’t change unless I change it.

3DS Max Design 2011 64-bit - Advantage Pack
Dell Precision T5500, Dual Six Core Xeon X5650 @ 2.67GHz, nVidia Quadro 5000, 24 GB RAM, Win 7 Enterprise 64-bit
Minneapolis, MN, USA

Dear Chris, Samab, and Ivan,

Have any of you figured out a workaround solution for the random-changing randomness of the multi-sub map yet?

I don’t know if any of you are still subscribed to this thread, now 6-7 months old, so I posted a new version regarding max2012 at http://area.autodesk.com/forum/t63919.

I have the same setup Chris does: hundreds of instances of a dozen proxies. From a quick test (and maybe I did it incorrectly, I don’t know), changing the Object ID of a proxy did not make any difference to the random-color assignment of the multi-sub map.

Has anyone found a script that you (Chris) were thinking of?

Thanks!
-Matt