3ds Max opens the Render Map dialog when you use Render Map on the sample slot right-click menu to render the map displayed in a sample slot.
These controls specify how many frames to render.
Every Nth Frame Renders a regular sampling of the animation. For example, a value of 8 includes only every eighth frame in the preview. Default=1 (every frame).
These controls specify the size of the rendered frames, in pixels.
These controls let you save the rendered map to a file.
When you click Save in the file dialog, you might see an additional dialog that gives you options specific to the file type you chose.