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View Full Version : Help understanding the physics of modelling



whtemple1959
11-09-2012, 01:10 PM
Hello,

I hope this is the right place and I hope I do not offend any one….I am trying to teach myself artistic skills so I have lots of questions.
I have been looking at a lot of scenery in blender, sketchup, etc.
I am curious as to why pine trees (in particular) look like cutouts which have been sliced half way through and then slid together? Is there a way to make them look more like a cone when viewed from above?

Thanks, Bill

ManOfSteel
11-10-2012, 12:53 AM
It depends on both the program's capabilities and also how much detail the modeler wants to put into the model. The more detail, the more work. That's because 3D models are made of a mesh of flat triangles or squares. The more detailed the model, the more triangles/squares (polygons) there are in the model. That means more memory has to be used to load the model, store it in active memory, and compute color, transparency, shininess, and bumpiness for every single polygon. So you see, it's much easier to make, load, display, and render a forest of trees that are made out of a few planes than it is to do the same for a forest where each tree is made out of thousands of polygons.

There are various tricks to ease your computer's workload when displaying or rendering a forest. You can use "billboards" which are photographs of real trees and put these in the distance where their two dimensional nature won't be noticed. However, because they're flat, they won't cast realistic shadows like a three dimensional model. You can put high detail trees in the foreground and lower detail trees in the background.

I don't use Blender, but I understand it can do very sophisticated things. Sketchup, however, is designed more for simple shapes. I've never seen a very realistic tree made with Sketchup. Other programs like Bryce 7, Vue, Carrara, Poser, and other more high end programs can make and/or import very highly detailed tree models.

Here are some examples. These could be used in Bryce, Vue, Poser, DAZ Studio, Carrara, and a few others.
Pred Pack - Fir Trees (http://www.daz3d.com/shop/pred-pack-fir-trees)
Lisa's Botanicals - Mighty Oak (http://www.daz3d.com/shop/lisa-s-botanicals-mighty-oak)

Midgardsormr
11-10-2012, 01:58 AM
ManOfSteel's right on the nose with the reason for the x-shaped tree. These scenes are meant to be viewed as though you're standing in them, not from straight above. If you're changing the perspective that drastically, you could absolutely replace all of those cards with different cards meant to be viewed from above. Or… hmm… a better approach might be to add a disc to the top of each one that's set up so as not to cast shadows. That way, you get the shadows from the original trees (a two-plane conifer will still cast a surprisingly reasonable shadow, even though most of it is empty air), but what you see is the new card, which completely, or nearly completely, obscures the X-trees. You might also be able to make the discs single-sided, so they only render if the camera is above them. That way, you preserve the original landscape if you move the camera back down to eye level. I know exactly how I'd do it in Maya, but I don't know what the best approach for Blender or Sketchup would be.

amberroberts09
11-10-2012, 08:53 AM
It depends on both the program's capabilities and also how much detail the modeler wants to put into the model. The more detail, the more work. That's because 3D models are made of a mesh of flat triangles or squares. The more detailed the model, the more triangles/squares (polygons) there are in the model. That means more memory has to be used to load the model, store it in active memory, and compute color, transparency, shininess, and bumpiness for every single polygon. So you see, it's much easier to make, load, display, and render a forest of trees that are made out of a few planes than it is to do the same for a forest where each tree is made out of thousands of polygons.

There are various tricks to ease your computer's workload when displaying or rendering a forest. You can use "billboards" which are photographs of real trees and put these in the distance where their two dimensional nature won't be noticed. However, because they're flat, they won't cast realistic shadows like a three dimensional model. You can put high detail trees in the foreground and lower detail trees in the background.

I don't use Blender, but I understand it can do very sophisticated things. Sketchup, however, is designed more for simple shapes. I've never seen a very realistic tree made with Sketchup. Other programs like Bryce 7, Vue, Carrara, Poser, and other more high end programs can make and/or import very highly detailed tree models.

Here are some examples. These could be used in Bryce, Vue, Poser, DAZ Studio, Carrara, and a few others.
Pred Pack - Fir Trees (http://www.daz3d.com/shop/pred-pack-fir-trees)
Lisa's Botanicals - Mighty Oak (http://www.daz3d.com/shop/lisa-s-botanicals-mighty-oak)


Yes you are right!!!