Let's talk about grass baby, just you and me, let's talk about grass :D

[kopperdrake]

Ok people...let's talk grass :)

Last project I decided to break from the traditional flat texture technique as the set of houses I had to visualise had the most boring frontage you could possibly ask for...big driveway, all the same type of paving, and NO plants :(

So I figured it was time to make real grass, to add *some* element of 3Dness to the whole thing. I used SASlite as part of LW 7.5's render-fodder armament, but that means no FPrime playing. It also means *ages* for it to calculate the shader before rendering.

And then I heard about Pawel's Grass Generator!

It seems to be polygon based, but has anyone used it with FPrime? Could anyone say if it were better/worse for grass production? I quite liked the idea of using a weight-map to decide where stuff was to grow. Can you treat the resultant geometry as you would standard geometry when it comes to lighting, for example, turn off radiosity for the grass to cut down on render times? Does it make use of a dual cpu setup?

It's a great price, I just wondered if it were worth adding to my arsenal of plugins :D

Dunk

[cathuria]

I think all of Pavel's tools are terrific, but they should be off the list of anyone who still gets cranked over polycount.
I've only used the grass generator a couple of times, but got good looking results with just a few re-do's and a little tweaking (the generator is fast & easy-to-use). But yes, it makes polygon grass, in varying degrees of complexity, but you'll need at least two poly's for each blade of grass (to get that curve to it) and those will also be double-sided. And a patch of lush lawn has one gawdallmitey lot of blades of grass. :eek:

[MooseDog]

hd-instance gives you some 3dness w/o the polygon hit :)

tho it is a volumetric renderer :eek: so won't play with fprime :( if that's a concern

of course for free is a point clone operation native to lw, but there you do have a tremendous poly hit.

should get you started. good luck.

[Wade]

It it's a still render do a comp. Make yourself one of the best lawns you ever saw high poly count and all then use that puppy over adn over as you would a sky or some other such compt image.

thanks what I think I might do. :o

[etobiason]

I wouldn't recommend Pawel's grass for that application because of the poly count. It's a great plug-in that gives you a lot of control over the look of the grass--but, you're making a lawn that's in front of a house. For a close up scene of, say, ants in a lawn Sas would suck, that's where Pawel's plug-in saves the day. But for a whole lawn, Sas looks pretty good. And if you think Sas takes time to render...try doing a whole lawn with Grass Generator...!

I must confess I never have finished a whole lawn in Grass Gen... I tried to, but my system got bogged down so much that I gave up.

[kopperdrake]

Thanks for the input guys :) Sounds like I'm best off sticking to SASLite for the lawn grass, comping one in won't work for me I think as every scene is slightly different in angle and lighting. The poly hit may be just too much...I'd thought of HD Instance and I can see myself buying that at some time in the near future, but for trees more than anything. I think maybe a flat poly lawn that gradually turns into a Grass Generator lawn near to the camera may work - I wonder if I could attach a weight map for the texture to the camera so the grass appears only within a certain diameter of the camera :)

Ideally everything would work in FPrime, but until FPrime works over a network then it'll remain for one-off images. This particular set of 4 houses were in a short street scene, with 4 seperate renders over a network - it had to be done with LW's native renderer, which at least let me use SASLite.

Cheers :)

[etobiason]

Grass generator does allow you to use weight maps to make the grass more concentrated in certain areas...but you can't parent the weight to a null or anything like that, because once the grass polys are made they are made, so the camera can't move around and have the more detailed grass stay with it.

[Exception]

I found sasquatch to be actually quite fast in certain circumstances...
see attached image, that is SAS grass and the grass renders in 40 seconds or so.

[etobiason]

Did you bake the shadows to a texture map and then use that texture map to color the grass?

To keep this relevant to kopperdrake's post, that's a neat trick to lower calculation time...then you don't need Sas to calculate LW shadows. You can even use sequential images to bake the shadows for an animation to a texture, allowing the full-scale animation to render much faster.

-e

[ravantra]

Interesting image.....Can I ask what it was for? Why is the guy drafting in the grass? Good grass....

[kopperdrake]

Yep - lovely image, but how did you get the shadows to render in such a short time? How many lightsources did you have? How do you bake a texture to be used by SasLite, will SasLite pick up on the luminosity channel in the surface it's being applied to?

[etobiason]

I'm not sure about Saslite, I've never used it, but after I tell you how to do it in Sasquatch you can see if Saslite will let you do it or not...

1. In Photoshop make an image with random grass colors, browns and greens. You can apply this as an image map to your grass.

2. Make a UV map for your ground plane. Apply the grass color image to the ground.

3. In your scene, apply surface baker and bake the shadows from the scene onto the image using your ground UV map.

4. Remove surface baker, remove the grass colors from your ground. Add your real ground texturing (like, dirt or whatever). Add your Sas grass, and apply the baked texture to the color. The grass will be colored darker where shadows are supposed to fall, but it won't have to calculate the shadows!

-e

[kopperdrake]

4. Remove surface baker, remove the grass colors from your ground. Add your real ground texturing (like, dirt or whatever). Add your Sas grass, and apply the baked texture to the color. The grass will be colored darker where shadows are supposed to fall, but it won't have to calculate the shadows!

-e

Thanks for the reply :) All the way up to step 4 makes sense, but in step 4, you mention applying the baked texture to the colour. Are you applying it to the colour of the grass surface in LW or the colour of the Sas grass in Sasquatch? If it's the latter then I don't think you can do that in SasLite...I'll have a play :)

Thanks again :)

Dunk

[etobiason]

Yeah... step four is where you apply the image map as the color of the grass in Sasquatch... I guess that's one drawback of saslite...

[kopperdrake]

Yep, that and the other drawback of no screamernet support :) I guess the next time I need an animated fly-through with grass I may be budgeting in the cost of Sasquatch :D

[Exception]

In response to your questions:

the image was made to test grass : ) I always like to make something a bit nicer out of my test renders. The guy is drafting in the grass because I feel its nicer to draft in the grass than in some stuffy office. And the kinda eerie building makes it a nice contrast between his serenity and the looming building.

I didnt bake anything, its just carefull tweaking of the settings in sasquatch. Its not sas lite though. I dont think that would make that big a difference. I didnt use any kind of map whatsoever. Theres just one directional light in the scene, and a skydome I believe, which is not affecting the grass.
Been a while since I did this tho...

[ravantra]

Again very nice test render

[pixym]

I found sasquatch to be actually quite fast in certain circumstances...
see attached image, that is SAS grass and the grass renders in 40 seconds or so.

Exception, Have you used the lite or the full version of Sasquash to generate such a amount of grass?

If it is the sas version, can you give me the setting, because I do not succeed in genrate such a amount of grass with saslite :(
In addition the plug seems to be poly size dependant... wich is not very good.

Thanks in advance for the reply.

Best.