This forum is shutting down! Please post new discussions at

Activities areas in output rasters smaller in area than reported in html

Hello all,

I was doing some calculations for the RIOS outputs for several watersheds. In order to do so, I converted the total portfolio raster output to shapefile. When doing the conversion, I was very careful not to simplify the polygons, so the resulting shapefile would have the same areas as the original raster. After that, I calculated the areas for the various activties, and then summed them up per watershed, and I noticed that the resulting areas are smaller than those in the html report. I'm enclosing a screenshot featuring a comparison between my calculations and the html report for one watershed as an example, but this happened to all the watersheds I ran the model for.

Does anyone have had this problem before?

Thanks in advance
1920 x 1080 - 350K


  • swolnyswolny Member, NatCap Staff
    Do you get the same area values when you calculate based on the original raster results?

    And it looks like in your table you're calculating square kilometers, where the HTML report is giving hectares - is this the case?

    ~ Stacie

  • JPrussmannJPrussmann Member
    edited February 2015
    Thanks swolny for your quick answer.

    Sorry, the values are in hectares. I just used the same field to recalculate the area in hectares, and forgot to change the header.

    I don't know how to calculate area in rasters. Is there a tool in ArcGIS to do this? I guess I could multiply the pixel count for each class by the pixel area, but that seems a little time consuming for several watersheds.
    Post edited by JPrussmann on
Sign In or Register to comment.