![]() |
![]() |
|
![]() ![]() ![]() |
To follow this tutorial you will need the scene tut1.max and its texture map files. If you have not it yet, get from our web site. Adding some trees. We are going to start opening the base scene tut1.max. From the 'cam1' camera, we make a render to see the scene from we start. By now, to follow in a right way the tutorial, don't unhide any object and render with the default options: ![]() We have a house with some hills to far and a road which go to the door. By now, a very simple and poor scene . We are going to start adding some trees: The Forest plugin is a parametric object which we may find in the 'Itoo Software' catergory. For this first part of the tutorial, you can use the freeware (Forest Lite) or comercial version (Forest Pro) of the plugin if you have it. First, we choose a top viewport to work more easily, make zoom near the house and create the Forest object clicking in any place near of it. By now, we only get a icon with a 'F' sign. This icon shows that the Forest object has not enough defined parameters to create the trees. ![]() ![]() We must have care of two points:
Tree Properties Now, we must define the main parameters for the vegetation. We exit from the object creation and go to the Modifiers panel to access the parameters of Forest object. First, we change the default name (Forest01) to other as: 'Trees 1'. Next, we show the Tree Properties rollout:
If we have worked before in 3D Studio Max with trees, we must have found two ways to do it: We can use details meshes, which at most of cases have a lot of of faces and vertices. It's possible to clone a few of them, but very soon we notice how the number of faces of scene grows very high and Max runs ver slowly. It's almost impossible to fill a large region with vegetation. Always, we can use a planar object with a texture of tree applied and an opacity map. They have very little faces, but also it's a hard work to fill an large area with them. Also, we must rotate manually the objects until they are looking the camera. Other variation is to use two crossed planes with the same texture. It gives a little more of 3d aspect, but it's far to be perfect. Forest can use any of these three methos: a single plane, two crossed or a custom mesh. For our tutorial scene, by now we are going to use One Plane, with the default option of Tree Properties rollout. Icon Size defines the size of the icon which appears when we create the object the first time o when there are not enough parameters to build trees. We may change it to see as runs or stay by now with the default value: 10. It's not important. Random Seed is any value which it's used to intialize the random numbers generator. Whem we change it, we obtain different variations of size, colour, etc. of the vegetation. By now, don't change it. Areas After finish with the general parameters, we are going to define the are inside trees must be created. This is achieved with one or more splines. Always in the top viewport, we create a rectangle around the house (don't care about size). We select again the Forest object and open the Area rollout. Click the 'Pick' button and pick the rectangle at view. After this, first trees are created inside defined aread. There are two important points about this:
We can modify the rectangle to see how the plugin changes automatically the distribution of trees. Always, we can collapse the rectangle to a editable spline and add more vertices, add other sub-splines, etc. This spline also defines the Z position of trees when not using surfaces. But all trees all placed over the same height position: the highest vertex of the spline. Sometimes, may be useful to define also an exclusion area. All trees inside this area are not created. This spline must be a different object of the include spline, and it's defined also with a 'Pick' button (see rollout). This option is only available in Forest Pro. In Forest Lite the button is disabled. Before to continue, we delete the rectangle we was using (it only was an example) and unhide the 'trees 1 spline' object (use the Display Panel->Unhide by Name) and pick it as 'Include Spline' for our Forest object. This spline is adjusted yet for distribute the trees around the thouse and road. We must get an image as this: ![]() Distribution Map By now, we have limited the area of trees. Next, we are going to define the way how the elements are distributed inside the area, their density, etc. We open the Distribution Map rollout:
The plugin comes with a default list of sample images. We open the combo list and may select any of them, seeing how the distribution of trees is affected. We have the following bitmaps to choose: Very Scattered, Scattered, Spread 1, Spread 2, Dense, Groups 1, Groups 2, Isle 1, Isle 2, Isle 3, Horizontal Band, Vertical Band, Random Bands, Vertical Line, Horizontal Line and Sine. The five firsts of list are used to make a random distribution with more or less density. The other images, follow patterns more defined. In Forest Pro, we can use also any other bitmap clicking in the button under 'File Name'. It's better this images will be little in size (100 x 100 pixels it's good) and grayscale or black/white format. Always, we can change the list of images (see the reference manual, Distribution Map section). With Forest Lite, we can use only the included images. And, how is applied this bitmap over the scene ?. In a very similar way of using textures in Max: The bitmap is scaled to a defined size and next is tiled in all directions. The size and offset parameters of this rollout define the values: In the size parameters, we give the size (in scene units) for bitmap. In the rollout sample of left, we have the image scaled over a surface of 240m x 100m. The 'Lock Aspect Ratio' checkbox locks the Y value to mantain the same X/Y aspect. If we change the X value, the Y size is adjusted automatically. In the left sample, the real size for bitmap will be 240x240 m because this checkbox is actived and the Y value of size is ignored. With Offset, we can change the position of the map over the scene to the desired position. If we test to use a small value for size, we will see how the density of trees and the number of trees grows. Also, the process time and geometry size of Forest object is more high. The plugin is optimized for speed (it may create over 50.000 trees / sec. in a Pentium II-350), but to avoid collapse 3D Studio, there are some limits: Always there is a minimum separation between trees. By default is 25% of width tree. For this,as are linked, when we change the width tree it's possible the size map changes automatically also to mantain the density limits. (You can do the test with this tutorial setting a 10m width tree value. The bitmap size will change to 250m x 250m: 100 pixels * 25% of 10m = 250 m. Remember to back the width value to 3m to follow the tutorial). If we like see how the trees are really following the shape of bitmap, we may use a more wide area and a more regular distribution map ('Group 1' or so). With this values, the effect is more noticeable. The last parameter of this rollout (Threshold) defines the threshold to convert a gray or color pixel to black or white. Evidently, only in color or grayscale bitmaps. To follow the tutorial right, please set the sample with a 'Spread 2' distribution. Size of 240m x 240m. Offset to 0,0. Minimum separation of 25% and Threshold to 50%. Looking to the camera We like to see how the trees are seen from the camera. We select the 'cam1' camera view and set the viewport in solid mode (Smooth+Highlights). Also, we open the material's editor and assign to the forest object the 'Trees' material. Well, by now the scene is not so bad.... but if we test to move the camera to one side, we will look how the flat trees give us a real sample of his nature (=:-o). We place the camera in the original position (use Undo) and open the Camera rollout:
Now, the perspective effect is very acceptable in all camera positions. Anyway, with camera motions, there are some limitations of this method and some tricks to help also:
In some scenes, may be very useful also use the Two Planes geometry for trees, and disable the option of 'Trees looking camera'. Of course, always the method to use depends of the scene we are making. Following with our tutorial scene. We are going to use the top viewport again to see a curious effect: normally, the field view of the camera only cover a small number of trees, respect to the forest area. There are a lot of resources and time wasted to build the rest of trees. Now, we enable the 'Limit to visibility' checkbox and see how the plugin limit the trees only the field view of the camera. If we move it, trees are created dinamically only in the required area. This is a unique feature of Forest which allows to define very large zones of vegetation with virtually millions of trees with a minimum workload of the computer. ![]() Also, it's possible to define a limit in distance from camera position (Far Clipping Plane). All trees placed to a distance higher this value are not created. Finally, the 'Expand' parameter allows to make the camera's field of view more wide. This is used in animations, with camera motion, where some trees may appear or disappear 'suddenly' by sides. With a value over 20%, this effects disappears totally. At this moment, we can place again at the view camera and make a render to see the result: ![]() Diversity Well, now we have a beatiful forest around our home, but we look that all trees are the same, and it's not a help to the realism of scene. We are going to apply some diversity with the Transform rollout:
In our scene, only we are going to apply a scale change. We can define a range for tree's height and other for tree's width o we can lock the aspect ratio of objects to mantain the same width/higth ratio. We enable the 'Lock Aspect Ratio' checkbox. Now, the values for height are ignored and we use 100% to 150% for width scale range. Automatically, each tree is built with a different size. ![]()
Also, we can use a random translation over the position of each tree, a value for the X axis and other for the Y axis. The values are defined as a percent of width's tree. This is useful when we use very dense distributions and the trees seem placed too regular inside the area. By last, we can also apply random rotations over the Z axis. Range goes from 0 to 359 degrees (this feature is deactivated if we are using the 'Trees looking camera' checkbox in the camera rollout). Speeding up the redrawing If we have a very dense vegetation, the scene may be very slow to redraw. With the Display rollout it's possible to optimize the job:
With the Mesh radio button, we can select the geometry used to create the trees: the custom mesh or a single plane. Only used when we are using custom meshes for the Forest object. With 'Simplification Level' we can reduce the number of trees created by the plugin. With the 0 value, all trees are built and with 1,2,etc. the number of trees is reduced progressively. Finally, we can limit the total number of trees in the Forest object (100.000 by default). It's used to avoid we make a distribution as dense to collapse 3D Studio creating trees.
|