Dynamic Paint and Freestyle
Dynamic Paint. Contrasting particle paint with a mysterious mesh object in the shape of a number moving on the z-axis. The mysterious mesh object is not shown to emphasize the Dynamic Paint process and not mesh movement. No Compositing Nodes. Image Above
Dynamic paint. Stopping particles with collision plane to show coincident locations.
Dynamic paint with Particle System.
A dynamic paint render. A cyan plane has been colored yellow with fading where the particles have hit the plane. Image above. Please click on image to see a larger version in a different browser window. The images were created by dynamic paint feature and then applied as a texture.
A Blender Render Node system showing a blur node. Please improve and customize.
Dynamic Paint Example. Canvas, Brush, Particle System. Please customize to your tastes. Image above. One panel is pinned to show data from more than one object. Note that using a particles system with dynamic paint may eliminate some options that the OP might find useful in a future version of Blender. The particles above seems to be used for location of the paint effect, disregarding size and shape. The mesh paint effect which is not a particles clearly respect the volume. Particles can be made in meshes by make real. Keep aware of physical forces.
Mysterious Mesh object brush with brush settings for dynamic paint. Not a particle. Image above.
Files created by Dynamic Paint based on particle system typically used as part of a Blender File render. 2 Images above. The yellow blobs show where the particle hit the plane.
and color a surface.
The Blender compositor can use a [blur node] to create a visual blur because it can recognize different objects by object id. A blur effect can be composed onto the image.
Freestyle and the compositor. Freestyle topic can be searched here at BSE.
- You may consider fire/smoke as well.
These three bullet points are high level information. Tutorials exists for these topics on video websites or you may find smaller explanations here at BSE