how to make snow edges follow terrain?

[hehe]

Hi I am wondering if anyone has any advice on making the edge of the snow line in TG2 that will follow the contour of the terrain so that the edge is not soft or blended but has fingers of snow that lay in the ravines and crevices and low lying areas at the snow line?

examples: http://vulcan.wr.usgs.gov/Imgs/Jpg/Shasta/Images/Shasta84_mount_shasta_with_shastina_1984.jpg

and here  http://www.amorahquanyin.com/images/shasta-ground.jpg

and here  http://www.geol.binghamton.edu/faculty/dickman/mt-fuji.jpg

Thank you very much for any advice

[FrankB]

I've done that once for TG0.9.

If you have World Machine, erode your terrain and have WM create you a thalus mask. Use that mask for your terrain to mask out the snow. This can give you a starting point.

Cheers,
Frank

[Oshyan]

Using simple slope constraints can get you a good part of the way to that effect. You should also experiment with "Intersect Underlying" in the Surface Layer.

- Oshyan

[oggyb]

Hi Oshyan, what does "intersect underlying" actually do?  And why does it need smoothing on?

M.

[Volker Harun]

When you load a terrain in worldmachine, you can run an erosion-filter on it.

Just put a fileoutput at the end of the node (called flowmap)  and you have a nice mask, where erosion (or snow) would walk along (snow would stay).

Applying this mask to a distributionshader (slope and altitude-settings) would make your effect.

V.Harun

[Matt]

As Oshyan suggests, "Intersect underlying" is designed to help with this kind of problem, but a couple of days ago I discovered that it is currently broken. I have now fixed it (for the next update), and I've been doing some tests with it to see if I can improve it while I'm there. I will try to put together some examples to explain its purpose and how to use it.

Matt

[dhavalmistry]

As Oshyan suggests, "Intersect underlying" is designed to help with this kind of problem, but a couple of days ago I discovered that it is currently broken. I have now fixed it (for the next update), and I've been doing some tests with it to see if I can improve it while I'm there. I will try to put together some examples to explain its purpose and how to use it.

Matt

thank you....this is a miracle....the main purpose of me coming to this forum at this time (1:00 AM) was to make new topic about intersect underlaying and here it is...first post in the forum....I didnt even have to make new topic....

[Matt]

Magic :-)

[VorpalBlade]

I bet you can generate a density map that follows the valleys down using WM. I may give this a try when I get home.

Edit: Volker beat me to the puch on the WM suggestion 

[reck]

As Oshyan suggests, "Intersect underlying" is designed to help with this kind of problem, but a couple of days ago I discovered that it is currently broken. I have now fixed it (for the next update), and I've been doing some tests with it to see if I can improve it while I'm there. I will try to put together some examples to explain its purpose and how to use it.

Matt

Can someone please explain to me what/how Intersect underlying does? It's been altered/improved in the latest update but I don't really understand what it does so I don't know when to use it. Thanks.

[Tangled-Universe]

Yes that would be really nice!
Maybe someone could also explain how to apply a flowmap 1:1 onto the terrain?
I've been struggling with it for a while. I know you have to set the size of your image the same as the size of your terrain in meters. But when I do that and I apply a bright blue/red colour to the mask the flowmap doesn't match the terrain at all. So anybody who knows?
Thanks in advance.

Martin

[bigben]

...Maybe someone could also explain how to apply a flowmap 1:1 onto the terrain?
I've been struggling with it for a while. I know you have to set the size of your image the same as the size of your terrain in meters. But when I do that and I apply a bright blue/red colour to the mask the flowmap doesn't match the terrain at all. So anybody who knows?

Usual things that go wrong:
Make sure placement of terrain and image are the same (centre or lower left), same coordinates and size.
Default projection for images is Through camera... needs to be PlanY to match the terrain.

The placement of snow will vary depending on a number of factors...
More snow in gullies ... start of snow season, snow in exposed areas melts more quickly
More snow on slopes/ridges ... running water from melting snow removes snow from gullies
No snow on ridges or in gullies ... last snow remaining in patches on steeper slopes shaded from the sun

[Harvey Birdman]

The placement of snow will vary depending on a number of factors...
More snow in gullies ... start of snow season, snow in exposed areas melts more quickly
More snow on slopes/ridges ... running water from melting snow removes snow from gullies
No snow on ridges or in gullies ... last snow remaining in patches on steeper slopes shaded from the sun

So Ben ... you seem to have a lot of experience with snow for an Aussie! What's the deal?

[FrankB]

Actually, "Intersect Underlying" is fixed with the latest version. Combined with slope and altitude constraints, this should give you what you need.
It's sorta tricky to exactly configure the feature for your specific terrain, (because Matt has yet to reveal how it really works), but you can get it done with a little try & error.

My take on it's functionality is, that it identifies either depressions or raises on the terrain.
The intersect zone defines how large the area is to take into account for identifying e.g. a depression. (you can define the room between your little fake stones as depressions, or use larger depressions such as found with mountain erosion.
Then, Intersect Shift shall let you define if the areas identified shall be lifted up or down by the specified amount.
I "guess" that minimum intersection shift is similair to an offset for the Intersection Shift.

Good luck,
Frank

[ADE]

done one here just last week....using intersect underlying and smooth bunged up to 2 with a little diplacement you can get snow that looks like its been shovelled into heaps...ok for snow plough scenes i spose
http://www.ashundar.com/index.php?action=dlattach;topic=3964.0;attach=173;image