To allow for the most flexibility an image is used. In it, each pixel represents a potential tree position, white pixels are tree locations, black pixels are empty space.

Using this method, we can define any distribution, from random surfaces to very regular groups.

Image

Forest can use a bitmap or a map as distribution image.

The plugin comes with some standard bitmaps included (Very Scattered, Scattered, Spread 1, Spread 2 and more). A custom bitmap can be selected as well by clicking the button under "Bitmap". The list of bitmaps is user customizable. In C:\Program Files\ItooSoft\forestpackpro\distmaps, there is a text file named "index.dat". It includes a list of the bitmap names and the associated file names.

To use a map, click the 'Map' button and select it from the Material/Map browser. All Max texture types are supported, from static bitmaps to animated noise maps. Use the "Clear" button to remove it.

The "Get UVW from Surface" parameter is described in the following section.

Density

Lets the user choose the scale of the distribution map in the scene. The map is applied in a manner similar to the way texture maps are applied in Max. The image is scaled according to the defined size, and tiled in all directions.

It's important to remember that the perimeter of the forest is always defined by a spline boundary. The distribution map only shows how the trees are arranged within that spline.

X/Y Units: defines the size of the distribution map in scene's units. If we use small values, we will see how the density of trees and the number of trees grows. Also, the process time and geometry size of the Forest object is higher. The plugin is optimized for speed, but to further speed up the plugin, here are some recommendations:

If the bitmap has fewer white pixels (less trees) but you set lower X/Y values, the density will be very high but most of the processing time will be wasted in computing gaps. To increase the density of trees, first set a higher density map, then lower the X/Y parameters. You can see in real-time some build parameters (such as density, number of trees) with the "Forest Stats" window. Open it clicking the "View Stats" button in the "General" rollout.

The "Stats" windows also alerts the user to some warning conditions such as when the area spline is not assigned, if the density is too high and other conditions.
There is a limit for the number of trees created in a Forest object. This parameter is defined in the "Display" rollout, and the default value is 500,000. Also, when the resulting mesh has more than 100,000 faces, Forest builds the trees for the viewport using a simplified geometry (adaptative display). All this behavior may be adjusted with the "Display" parameters.

X/Y Pixels: these values are used to adjust the density in procedural maps, without modifying the X/Y Units scale. These parameters are locked when using bitmaps, using the number of pixels of the image as default value.

Get UVW from Surface (image options): As alternative of using the X/Y values to define the density of the distribution map, it's possible to get the scale from the UVW coordinates of the surface. This mode is useful to adjust the position of trees in more precise way, using a surface map as reference. To use this mode, a surface object must be defined in the "Surface" rollout.

Fit to scene: allows the user to fit the map exactly over a position on the scene, automatically adjusting the offset and size values. Use Pick Start/Pick End to select on the scene the position of two opposite corners of the map. This tool is useful for adjusting maps which represent exact positions of elements in the image, such as modified aerial views using a white pixel per tree.

Lock Aspect Ratio: locks the X/Y aspect of the map. When this checkbox is enabled, the Y size for map is ignored and only the X value is used.

Offset: adjust the offset of the map over the scene. Values are in the scene's units.

Threshold: defines how the image pixels are converted to black/white levels when the bitmap is in grayscale or color mode.

Rotation: rotates the distribution map a specific number of degrees.

Max density: set the limit of possible tree positions in the area (by default 10 million). Take care: this includes both white and black pixels in the distribution map, so you may reach the density limit using an empty map and low X/Y values, but not get a single tree in the scene.

Draw Gizmo Corners: draw the corners of the distribution map to adjust it more easily.

(continues on Distribution Map 2)