Similar to NDVI, the Satamap Vegetation Index (SVI) exposes variability in vegetation by exploiting the difference in reflectance in the red and near infrared bands. SVI also uses the green band to help mitigate the effects of soil colour.
PCT Satamap offer three colour scales to represent the information: Equal, Low and High. In Agworld, because this is a free feature, we only show SVI Equal. SVI Equal distributes SVI values evenly across the colour scale, whereas SVI Low gives bias to low biomass crops and SVI High bias to high biomass crops. This allows maximum information to be extracted from the imagery.
If your map is primarily one colour, it would be because the biomass (or greenness) in the field is very low (or bare soil) and these small values are not represented on the SVI Equal colour scale. Low biomass or emerging vegetation should show up as white/yellow and then move up the colour scale from there.
In the free version, available in Agworld, you cannot compare growth between two dates, or change the SVI scale so that you can identify crop growth in low biomass situations. This, and many other features are available in PCT Satamap.