1a45265a_rigger_Rally_Map_XML_Reference__description
[attribute] spritecount [example value] 1 [possible values] low positive integer (not zero) [description] 
Number of images/axes used for each vegetation instance. The more images per instance you use, the better the result will look. But this comes with a high price: You can seriously increase rendering performance by cutting down this value. (Using more than 3 axes rarely makes sense anyway.)
Trigger Rally Map XML Reference
description