Distribution Modifier

 Distribution Modifiers are a very simple object. In the viewport they consist of a spherical fall-off field. When you drag and drop one into the Filter by Modifier field on a SurfaceSPREAD object on the Distribution tab and increase the intensity clones that are within the falloff field will disappear. Rather than creating the modifier manually and dragging it into the Filter by Modifier field on a SurfaceSPREAD object you can press the Add Modifier button which will create the Modifier for you and add it to the field.

You can control the transition between areas inside the falloff and areas outside by adjusting the spline curve. By adjusting the spline you can have a very hard transition or you can have the transition very soft (default is soft). Distribution Modifiers would be used where you quickly want to remove clones from an area without having to resort to other methods like creating vertex maps. Cool effects can also be achieved by animating the position of the Distribution Modifier and or animating the Size of the falloff. Once thing missing that I would like to see is an Invert option so that clones outside of the falloff field are hidden.

The image below shows 2 Distribution modifiers in action. The size of the falloff is the same but the spline is different. With one Distribution Modifier there are no clones in the falloff area but in the other the transition is very soft.

Distribution Modifier in Action

Scale Modifier

 Scale Modifiers are similar to Distribution Modifiers but rather than making clones disappear they change the scale of clones. Scale Modifiers are added to the Filter by Modifier field on a SurfaceSPREAD object on Effects tab. Once added you can drag the intensity slider on the SurfaceSPREAD object to increase the scale of the clones. But what if you want to reduce the scale? No problem. On the Scale Modifier you can change the intensity slider to negative values. The image below is a bit of fun where I have used the Scale Modifier to make the Cactus plants in the middle of the scene progressively larger.

Scale Modifier in Action

Wire Object

 The Wire Object is a bonus object and pretty much unrelated to the other SurfaceSPREAD objects. What it does is create a spline from a series of null objects. You can then use this spline as you would any other spline. The Wire Object has similar spline options to regular splines. One advantage of using Null objects and a Wire Object rather than PLA is that when you animate the position of null objects you can edit the F-Curve. Point animation is linear interpolation only and there is no F-Curve.

The fun starts once you start cloning a null object with a SurfaceSPREAD and then drag an drop a Wire Object into the Virtual Parent field. The result of a null cloned on to sphere is this. (SweepNURBS and circle spline added). Notice the Object Manager Hierarchy in the image below. The SurfaceSPREAD object is in the place where the path spline goes. Because I have used the Virtual Parent option on the SurfaceSPREAD object and dragged the Wire Object into the Virtual Parent field, the SweepNURBS object treats the SurfaceSPREAD object as a spline.

Wire Object in Action

The Wire Object opens up new possibilities with animating splines. Normal Splines can only be animated by applying a PLA (Point Level Animation) to their points. This means you don´t get F-Curves. By using and animating Null objects you can edit the position F-Curves. The Wire Object gives allow Bezier Splines to be used and their Tangent handles can be animated. Very cool.

Distribution Override Tag

 The Distribution Override Tag available from the Tags menu can be applied to cloned objects i.e. objects that are child objects of a SurfaceSPREAD object. When you have a number of objects being cloned you may not want them to have the same Distribution filter settings. This is where the tag comes in. The image below shows where I have used the tag on the tree stump object and enabled the minimum Altitude option. The tree stumps are now only on the mountain at altitudes over 50m. I have also used the Maximum Slope option so that there are no stumps in steep areas. On the tree trunks I used the Maximum Altitude option and made it so that there were no tree trunks over 30m in altitude. (The grass is HAIR)

Distribution Override Tag in Action