Create a seamless raster from multiple polygons?

Question

I have been attempting to create a total cover map of a 4x4 km target area.

I clipped the target area to my desired size and used the create polygon feature of ArcGIS to define all of the areas as 'meadow', 'roadside', 'uninhabitable' and 'wooded' ( I was very careful to make sure that all of my vertices on my multiple polygon layers connected so that there was no undefined space) .

I am trying to convert this entire 4x4 section into a seamless ASCII grid file so that it can be run by the program Circuitscape.

I have tried converting all of the polygons into individual rasters and running the mosaic rasters tool provided by ArcGIS, but this results in a huge mess.

any advice that can be offered?

Answer 1

With my limited exposure to Circuitscape, I would try the following workflow. I presume your polygons are to represent friction/resistance. I think the first thing is to make sure your polygons are coded properly. For this I would first use Dissolve tool as multipart option is True to make sure I have only four (or as many as your land covers) polygons representing your land covers. Then I would add and calculate a Float field to assign resistances, say wooded = 0.1, roadside = 9, etc., according to your conceptualisation. Following this, I can utilise Polygon to Raster tool by selecting previously created float field as the Value Field to have my resistance layer which will be a float raster.

As far as I can tell, you do not necessarily need a seamless raster to have the program run properly (NO DATA is treated as impassable) and one resistance raster will be sufficient (no need to create multiple rasters and mosaicking)

Answer 2

any advice that can be offered?

According to the Circuitscape web site

Oct 2013- Circuitscape can now be called from an ArcGIS toolbox. No more converting input grids to ASCII format! Just install the ArcGIS toolbox from our downloads page when you install Circuitscape.

So you don't need to convert to Arc/Info ASCII Grid at all.