Drops scattered across the tin surface using the Maxwell Scatter feature

The Maxwell Scatter extension allows you to distribute instances of an object across the surface of another object randomly, while providing control over the random distribution. The object may even be an MXS Reference.

Applying Maxwell Scatter

Depending on whether you work in Maxwell Studio or via a plugin, the steps may differ slightly but the principles remain the same - Maxwell Scatter is applied as a property to the object. Please see your plugin documentation for details. For Maxwell Studio, the procedure is:

select a piece of geometry and apply the MaxwellScatter modifier to it. You can do this either by right-clicking on an object in the Object List panel and choosing Apply Object Modifier Extension>MaxwellScatter, or you can click the New button in the Modifiers section in the Attributes panel.

You will see the MaxwellScatter modifier and its parameters in that object's Modifiers section. You can also click the little white dot to the left of the modifier to disable/enable it. You can apply more than one Scatter modifier to the same object - each modifier will use its own settings.

The parameters are similar to the ones found in the Maxwell Grass extension.

The MaxwellScatter parameters panel (left). The vectors in the viewport (right) display the distribution, scale and orientation of the instances. Click the image for the full size version.

Primitive

Object

Choose the object or MXS Reference object in the scene that will be instanced on the surface of the main object.

Inherit ObjectID

When enabled, each instance of the object inherits the object's ObjectID color, while when disabled, each individual instance generates a different ObjectID color.

Scatter Density parameters

Density

Controls the number of instances of the object per square meter.

Density map

Specifies a grey-scale map to control where the instances will be created. Fully white areas will have the maximum number of instances you specify in the Density parameter. Fully black areas will have no instances at all.

Random Seed

This number is used to generate the random distribution of the instances. If you use several Scatter extensions on the same object, make sure the seed number is different for all of them to produce a totally different random distribution and avoid several instances being placed in the same location.

Remove overlaps

This option automatically removes the overlapped instances to ensure a distribution without collisions or overlaps.

Enabling the Remove Overlaps option (left) ensures none of the instances are overlapping in the final distribution (right)

Scale parameters

Scale X, Y and Z

Scales the primitive in the X, Y and Z axis according to this factor.

Scale map

Loads a greyscale map to control the Scale in X, Y and Z globally. Fully white areas will represent the maximum scale specified, while fully black areas will represent scale zero.

Scale X, Y and Z variation

Randomizes the scale of each individual instance, specifying the range of possible scale values as a percentage of the nominal Scale parameter. For example, if the Scale Y is set to 1 and the Scale Y Variation parameter is set to 50%, the height in Y of the generated instances will be randomized between 0.5 and 1.5 of its nominal height.

Rotation parameters

Rotation X, Y and Z

Rotates the primitive in the X, Y and Z axis according to this angle value.

Rotation map

Loads a greyscale map to control the Rotation in X, Y and Z globally. Fully white areas will represent the maximum rotation specified, while fully black areas will represent rotation zero.

Rotation X, Y and Z variation

Randomizes the orientation of each individual instance, specifying the range of possible rotation values as a percentage of the nominal Rotation parameter. For example if Rotation Y is set to 180º and Rotation Y Variation parameter is set to 50%, the orientation in Y of the generated instances will be randomized between 90º and 270º.

Grow Towards World-Y

This percentage allows you to modify the direction of the Y-axis (up) of the scattered objects:

Perpendicular to the surface when set to 0%
World-Y axis (up) when set to 100%

If you set the value to 0%, the main direction will be the base polygon normal direction (and then all the variations are applied); if you set the value to 100%, that main direction will be World-Y, but then, in the intermediate values is where it gets interesting, as a 50% value gives direction in between the normal and the world-Y, which is more natural in the case of plants. After the main growth direction is set, the variations are applied.

Level of Detail parameters

This option allows you to optimize your scene by rendering more instances near the camera and gradually fewer as the distance from the camera increases. The LOD allows you to save RAM when rendering and can be very useful, especially for scenes where the camera is placed closer to the object and looking away towards the horizon.

Note that the LOD will be applied to the active camera in the scene.

Min Distance

The distance from the camera where the level of detail distribution -LOD- won't have any effect. 100% of the instances will be rendered inside this distance, as specified in the Scatter Density parameter.

Max Distance

The distance at which the instances' density will have reached the density specified in the Max Distance Density parameter (below). Between the Min Distance and the Max Distance there is a falloff in the number of instances, until they reach the Max Distance Density.

Max Distance Density

The percentage of instances Density you wish to have when the Max Distance is reached. For example if the Scatter Density parameter is set to 100 and Max Distance Density is set to 10%, then 10 instances will be placed at the Max Distance.

Display parameters

The instances in the Studio viewport are displayed as vectors scattered over the object surface according to the random distribution (see illustration above). These parameters are useful to optimize the viewport speed and only affect the Studio viewport display and not the render.

Display Percent

The percentage of instances to show in the viewport.

Display Max. Instances

The maximum number of instances to display in the viewport.

A note on memory consumption

It is important to be aware of the RAM consumption when generating replicas of objects automatically, otherwise it is easy to produce much more objects than your computer can handle - for instance, if you have an object (i.e. a tree) composed of 8000 objects and use MaxwellScatter to distribute 27000 replicas of the tree object across a landscape, internally the system must generate more than 216 million objects, which can hang your computer if you don't have enough RAM . If instead the tree object is merged and left as just 25 objects, the system can handle the scene without problems and the result will be the same.

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