I'm running a tool developing stream power index values and had a range from -3.xx to +6.xxx. I'm wondering where the negative SPI values come from?
The negative values are appearing by otherwise high positive main convergent flows and were symbolized in white whereas the colored are positive values.
you have published this in the general gis section. So you want a more targeted audience like Hydro or the Spatial Analyst place? What tools did you use to generate your index?