PDA

View Full Version : Saslite grass


Willax
11-08-2002, 06:51 PM
I have a ground object that is 150 meters on all sides. I am trying to use Saslite to make grass on it, but when I set the length to be short (about 3.5% or 88.59mm) it doesn't show up as thick grass with color. it only shows as a few strands here and there with no color. I have fur density at 200% and coarseness at 80% with no clumping. Can someone tell me how to get a better grass look on this size of ground or do I need to make smaller objects and piece them together? Oh and the surface of the object is divided in two with the front surface which I want to put the grass on called grass_front. I am trying to apply the grass to this surface only and selected that in properties. Although it's not very clear, the grass area is shown in my icon to the left. The character is only 1.65 meters tall. Any help would be appreciated Willax

Oh, and one more thing, can anyone tell me how I can post an image in my message?

dark_lotus
11-09-2002, 12:41 AM
Well as for the sas problem, I'd increase the length of the grass, if that doesn't work then try increasing the number of polygons that that surface has (ie Sub-Divide).

As for an image, when you type your message, below where you type your message, you will see 4 checkboxes then an attach file dialouge.

Click browse and make sure the file is under 50kb.

Willax
11-09-2002, 01:24 AM
I have tried the subdivide with about 100 polygons and also with only 4 and still get the same results. However, I have done other objects with fur/hair and it's as bushy as can be.

In the reply dialog there is a button that says IMG (insert message) but when I press that it gives me a requester I don't understand. It says script prompt then this : http://

Is there somewhere that explains this process?

Cf!
11-09-2002, 02:52 AM
I think you should increase the length to about 15%. Here's a scene I threw together quick. It's based on your scene description. I thought some other people might like to see it if they are having trouble with saslite.

Cf!
11-09-2002, 02:54 AM
here's a render

Willax
11-09-2002, 03:18 AM
Thanks Cf!

I played around a bit with the settings and the size of the ground object. It seems that when i have a smaller ground object the grass comes out ok, but when it is hughe like 150 meters I have the problem. Here is the file with the 150 ground. pretty ugly.

http://home1.gte.net/res0hk2e/grasspicsmall.gif

I downloaded your grass scene and when I rendered it out the grass was way too tall. Almost covered the dummy model. When I made it smaller, approximately 5% I got the right length but it was very sparse as it appears in my picture above. I'm very confused about the ground size issue with saslite. Willax

Cf!
11-09-2002, 04:04 AM
Wooaaa! I just tried it and it doesnt look like my posted render does it. I'll fix it then repost the scene. sorry about that.

Willax
11-09-2002, 04:37 AM
This is the render with the smaller ground and the applied grass settings, with the grass being set at about 30%

http://home1.gte.net/res0hk2e/grasspic2.gif

it seems that the size of the object is crucial in the way the grass appears. the larger the object, the less efficient the grass coverage is if you want the grass to be short. The reason this is important in my scene is because when I load trees and buildings and characters on top of the 150 meter ground they are already set at the correct size. I don't want to have to resize them to fit the ground size and grass. Willax

Cf!
11-09-2002, 05:04 AM
Slice up your ground plane and paste the different sections into different layers. Adjust sas to your liking, then paste to other layers if they are evenly sized. if they are not evenly sized you will need to tweak them all so they look the same when rendered. you have up to 8 instances. you should be able to get a result more like you are looking for. If you are doing an animation you will likely be getting some unexceptable render times.

mohh
11-09-2002, 05:05 AM
The thing to remember when using this plugin is that the length is a percentage of the size of the object. So if you change the size of your object, you will have to adjust the percentage too. You'll have to play around with it to get the look that you want. For your scene, try increasing the length to about 50% to see what you get. Then adjust either up or down to your taste.

SplineGod
11-09-2002, 05:15 AM
Heres some simple tips to help:
1. Make your ground color a SIMILAR color to your grass color. This will help blend the grass in better with the ground and allow you to decrease the density.
2. The fur length is NOT linear. Small changes have a big effect.
3. Lower the clump size and the clump amount. The number of fibers doesnt change but this spreads them out more.
4. Start with a modest density and then work your way up if you have to.
5. Dont use large ground polys. Treat the scene like a movie set and dont make things bigger then they need to to make a shot work.
6. Density and fur length have the largest hits on render times.
7. You can apply more then once instance of saslite on a surface. This is useful to add some randomness to the scene. When you d

Howzat
11-09-2002, 09:57 AM
So it seems that you are all saying that there is no way to cover the cube with short grass the way Willax wants?
ie. With short grass and high-density as one surface?? That seems crazy, why is it so difficult?

SplineGod
11-09-2002, 10:22 AM
I didnt say he couldnt. The render times could get outrageous.
Keep in mind this is a LITE version of the real thing.

Willax
11-09-2002, 03:48 PM
:)
Thanks again everyone for their help and direction in this problem I was having. After taking to heart your suggestions and with much experimentation, I have found a work around , I think.
http://home1.gte.net/res0hk2e/grasspic3.jpg
With a large polygon surface, I had to split the top into smaller sections and name them as individual surfaces ie: grass1, grass2, etc. Then in layout, I was able to assign different lengths to each surface as needed, shown in picture. The surface where the character is standing and the surfaces behind him are all the same setting but actually 6 separate surfaces. I'll just have to be careful about how I plan large surfaces and using saslite on it. Maybe someday I'll be able to afford the full product :drool:
Thanks again for all the help. It sure made things easier to work on. :thumbsup: Willax

SplineGod
11-09-2002, 05:26 PM
The solution you found is an easy one. Its easy enough to use the stencil tool to cut up your ground into more random looking areas too. You can still tell saslite to apply grass to all surfaces at once or do what you did and apply an instance of sas to each surface. An easy thing to do is apply sas once and then copy and paste it several times then go in and slightly change each setting for the different surfaces....you probably wont need the full version for a long time. :)

Wesball
11-09-2002, 07:57 PM
I saw on one reply that you set the courseness to 80%... I almost never set it below 200% or 300%

set the length to whatever you want... and the coursneess will make the grass blades really wide. The more course it is the less density you will need also... :-)

hope it helps.

Wesball
11-09-2002, 08:02 PM
a test render I did for some grass is on the top left.

I used full sasquatch... so I don't think you can have the random color with saslite, but the in regards to the size of the grass.... should be the same.

courseness was 300% I think.

http://www.mindscheme.netfirms.com/Images/bear1.jpg

SplineGod
11-09-2002, 08:18 PM
Setting the courseness higher does help but can also end up being too thick. Values can go well beyond 100% for some settings. Setting the surface color to something similar to the hair color (with some texturing) helps alot.
You can do random hair color in saslite two ways:
Random Hue and adding more then once instance of saslite to the surface and giving each instance different colors and settings.

Yiorgz
11-09-2002, 11:08 PM
I've posted some stuff about what I've found with saslite and a few people have responded so you might want to check out these threads.

Saslite.. general querkiness with extremely large sized (1:1 scale) objects..

http://www.cgtalk.com/showthread.php?s=&threadid=19978&highlight=saslite

Saslite and GI (radiosity) rendering.. what I've found..

http://www.cgtalk.com/showthread.php?s=&threadid=24935&highlight=saslite

Just a brief post on object size (in amongst others)

http://www.cgtalk.com/showthread.php?s=&threadid=21577&highlight=saslite

In short though... a workaround is to set up your scene (all except the ground) exactly how you want it. But ... be sure to have a NULL object that all your other objects area parented to.

Next set up your ground plane on a smaller sized object, get your grass looking right for your shot, then resize your NULL that has all your other objects as children so that they match the ratio of the grass.

Lock your sizing null with scene editor and then you can start animating your objects.

SplineGod
11-10-2002, 01:05 AM
Thats some great info, thanks!
Another piece of advice, some stuff Ive learned on actual production work:
1. Model things to size where applicable...like characters, vehicles and so on. This changes however with world sized situtations. Dont model things that are HUGE to actual size. Lightwave has a limited amount of floating point space and you can run into some issues on very large scaled scenes.
2. Pretend that your scene is being setup on a stage somewhere. How would you create the illusion of a large set when you dont have the actual space....fake it! :) In other words a 80meter diameter world at 200 meters looks the same as a world 8000 miles across and 5000 miles away.
3. Keep the scenes as close to the origin as you can. Issues again can come up where your objects are very far from the origin which means a huge scene again.
4. Model for the shot. Dont waste time making huge sets that are "accurate". Making things to just look good in your shot is a faster way and more flexible way to do things.

CGTalk Moderation
01-13-2006, 09:00 PM
This thread has been automatically closed as it remained inactive for 12 months. If you wish to continue the discussion, please create a new thread in the appropriate forum.