my first render with maxwell

[panpanndundu]

this is my first images render with maxwell, i've used sketch up for modeling..please give me some suggestions..cuz i am still confused with the ibl and displacement settings...thanxz before...

[Brodie Geers]

nice start. what are you confused about regarding the settings?

 

-brodie

[panpanndundu]

thanx.. i,ve confused with displacement setting of the material..just like grass and carpet displacement...hope you can help me to learn about the displacement.....

 

pandu.

[Brodie Geers]

Well, I'd definitely recommend reading the manual, which is quite good. That said, there are just a few parameters. You insert into the Map slot, your displacement map of course. Then your height can be set in either a percentage (I almost never find this useful except in the material preview scenes because they're very small) or in cm (it's very important that everything be modeled to scale in Maxwell). The more displacement the longer the render time will be.

 

Your Offset determines where the low and high point of the displacement are. Some maps use 50% gray as the 0 point (darker will create cavities, lighter makes hills). If this is the case you want your Offset to be .5. Other maps use black to be the 0 point (anything lighter than black will be a hill), then your offset should be 0.

 

Then you've got Gain which is basically how precise you want Maxwell to treat your displacement. The higher the number the more precise the displacement and the longer the render time. Usually this is between 16 and 80. If you want to be REALLY precise you can check the Adaptive box which maxes out the precision but can really slow down render times. Finally Smoothing will just smooth out the displacement so there are no sharp edges (useful for most things like rock, but not useful for something like grass).

 

BTW, I've done grass displacement. If you can get around it, I recommend doing something else. It makes for a worse case scenario in terms of displacement (you have a very tall displacment which requires a lot of precision so render times are greatly increased) and it doesn't look that good since all the grass is sticking straight up.

 

Also, this is very important. Your Gain is closely related to the size of your geometry. Displacement geometry should be subdivided. The closer you can get to small squares (long triangles are bad) the better your displacement will look and the lower your Gain can be.

 

-Brodie

[panpanndundu]

thanx brodie.. that will help me much..

cuz sometime the preview and the render just quietly different.. do i have to divide the large object to get a better result? cuz same setting material displacement, have different result with different object.

 

thanx before.

pandu

[Brodie Geers]

Which modeling program are you using?

 

Think of it this way (I think this is pretty close to how it works). What displacement does is push out your plane to make a shape (let's say brick). If you just have one big plane with 4 corners, your displacement wont do anything at all because it doesn't have enough vertices to work with. That's what Gain is for. The higher your Gain the more subdivisions maxwell will do at render time (without any extra work on your part). Now with those subdivisions maxwell can actually start bumping out finer details in the wall. But creating these subdivisions at render time slows down your rendering. So you want to help it out by creating your own subdivisions, then your Gain can be brought down considerably.

 

For something like brick or rock I'd probably start with subdivisions of 3"-6" (so a large plane would be cut into anything from 3"x3" up to 6"x6" squares) and a Gain of 16. Then do some tests and adjust from there.

 

What commonly happens if you don't know about this (as happened to me) is you leave your large plane and set your Gain at, say 32. Maxwell will do some subdividing but not enough for any detail so you'll notice nothing. So then you crank the displacement up until you see it doing something but it is only creating large random wavy patterns (because it doesn't have enough vertices to create any detail).

 

-Brodie

[panpanndundu]

i used sketchup 8 for modeling. did it effected for displacement setting?

the shape was not a brick, but a roof and grass. i just checked the addaptive but the render time getting slow...

Btw your replies help me for understanding the displacement..

sorry my english was bad.

 

thanx

pandu

[Brodie Geers]

Bah, your english is just fine. Keep in mind that Adaptive is almost always NOT what you want to use, because it slows down the rendering SO much. Use it only as a last resort or as a test (sometimes i'll do a test with adaptive to see what the highest quality will look like, then I'll go through tests with different levels of Gain until I get something reasonably close).

 

SketchUp doesn't have many good options for subdividing unfortunately (I'm a SU user myself). The Subdivide and Smooth plugin has a Subdivide option but it's not meant for or very good for displacement because it subdivides into triangles (like I mentioned before, you want squares or something close to it). I have two methods for this.

 

1. You can use SU's sandbox tools, particularly the "From Scratch" tool. This will give you a plane of whatever size you need and it will be subdivided into whatever size squares you choose. The disadvantage is that you have to make a large flat plane an then position it where you need it to go and cut out areas you don't need.

 

2. The solution I typically use is to use the Soap Skin & Bubble plugin (download the .zip file from here http://www.tensile-structures.de/sb_software.html ). This is a great plugin. For example when doing this for grass, here's what I do.

 

Just create your grass plane as you normally would. Double click the plane to select the entire plane as well as it's borders. Then hold down Shift and click the plane again once - this will deselect the plane but you'll still have it's borders selected. Now choose the Skin option from the Soap Skin & Bubble plugin toolbar. It will show you a preview of how it will subdivide the plane it's about to create. You can type in different numbers to adjust the size of the subdivision. Hit enter and it will go through a routine subdividing the whole plane it just created. But even though it created a new plane for you your old plane is still there so you need to delete it (either move your Skin plane out of the way, delete, and move it back or Cut the Skin plan, delete the old plane, and Paste In Place).

 

The advantage is that you don't have to go cutting anything. Even if you had holes in your plane (maybe mulch or sidewalks or something), it will cut around those and works great.

 

-Brodie

[panpanndundu]

thanx..

i have used soap skin and bubble plugin too. but i usually use it for make a dome ceiling. i never thought that can be used to divide the plane... wow thats great solution.. thanx..

pandu