(c) 1999 Itoo Software www.itoosoft.com

Reference FAQ

Can i use Forest for other scenes instead group of trees ?

Of course. Forest is a powerful parametric scatter and you can use it to create groups of rocks, clouds, large crowds of people, etc. Visit the image gallery for good samples.

Can i use Forest Lite for my commercial projects ?

Yes. You can use it for all you like. But, evidently, we will appreciate you colaboration updating it to Forest Pro. So, we will may support the product and release new versions in the future.

What are the differences between Forest Lite and Pro ?

The Lite version cannot use:

  • Custom meshes
  • Exclusion splines
  • Random ID materials
  • Surfaces
  • Custom distribution maps

The rest of features are identical.

Can i use Forest Pro with my scenes created with Forest Lite?

Without problems. Forest Pro is installed replacing to Forest Lite, an all the files are compatible.

Is there some limit in the number of tress that may contain a Forest object ?

No. Only the limit of 3D Studio and our computer. Anyway, it's important to be careful when setting the values for the Distribution Map, because if we use high values of density, we will notice very soon the excesive load of work for Max. In these cases, we need to use the Display Panel to speed up the redrawing of viewports and permits to build all trees only in the render stage.

The same consideration is applied in use of very complex Custom Meshes of with a lot of trees.

How can be optimized the render time when there are many thousands of trees ?

When we use opacity maps and there are a lot of overlapped objects in the view, render time may be high. This is a limitation of 3D Studio, but there are some tricks to speed up it:

  • While less objects are overlapped, we will obtain a best render time. So, the low altitude views will be slower than high altitude views with a more wide field of view. In the first case, we can limit the trees at distance (Camera Panel -> Far clipping plane), because the more distant trees will not be seen anyway.
  • For the most far trees, we can use a custom mesh built with a shape similar to the silhouette of tree and deactivating the opacitiy map for the Forest object. The render will be accelerated a lot, but the trick will not be noticeable. Probably, we will need to adjust the texture map to cover perefectly all the shape. Also, it's important to use a custom mesh with little faces, only the necessary to give a good effect from the view distance which camera are placed.

Because the shadows are squared ?

I we use the default geometry of Forest, the trees are created with single planar faces and, evidently, its projected shadow has the same form. This problem only exists if we use lights with 'Shadow Map'. With 'Raytrace Shadow' lights, the projection for opacity mapped objects is right solved, but the render time is higher.

How may we obtain realistic shadow without raytracing lights ?

There are some tricks, every one has its own advantages and inconvenients:

The most simple: don't use shadows for Forest objects. This solution seems trivial, but there are some scenes in which is not feeled the absence of shadows, specially with shrubs and low trees.

Using diffuse shadows. Setting the 'Sample Range' for shadows (in light parameters) to 8 or 10, the effect will be enough diffuse to mask the geometry of tree.

Using custom meshes for the geometry tree. This solution is only applicable for little trees or a very simple mesh.Also, we can use real meshes for trees in near view and diffuse shadows for far elements.

We can use a light projecting a bitmap which have the appearance of the shadow (it's easy to use the opacity map of the tree) and using negative values for the multiplier (this way, the light add dark to the scene instead luminosity). It's necessary adjust very well the position of this light and must be created one per tree. This method only it's useful and convenient if we have a few of trees or apply the lights only to some of them.

It's possible to create a second Forest object with the same options from original, but using a Custom Mesh which represents the shape of tree. In this object, we must deactivate the 'Tree looking camera' option (from Camera Panel) and rotate the trees until will be looking to the light which projects shadows (the trees rotates using the Transform Panel, setting the same value in max and min rotate parameter). This object must have also a material fully transparent (we cannot see it in the render, only for shadow!). This way, we have two Forest objects: one for see in render and the other for create shadows.

In a lot of scenes, also is useful to use 'Two Planes' in the tree's geometry because the projected shadow is more compact.

Also, in Itoo Software we following researching new methods to create real shadows with planar textured objects (and now with the new features of Max 3)

Is it possible to use the RealPeople's trees with Forest ?

No. Realpeople uses a propietary system to generate the tree's geometry and its material. Anyway, we will like to add this feature in the future, because the two plugins working together may be amazing.

Why when loading Forest's scenes, created in Max 2.5, in Max 3 the program exits to Windows ?

This problem has been detected in some scenes. A way to solve, it's to load the scene in Max 2.5, deactivate the surfaces of Forest objects and save them. Load in Max 3 and link the surfaces again. Now, we can save the scene normally in Max 3.