I have produced ASCII files in MaxEnt. These files are able to be loaded into Arcmap10.1 and display as an image, but I cannot interpret them or create them into a polygon for further analysis. I have read some forums that say I need to add spatial reference and calculate statistics (http://gis.utah.gov/wp-content/uploads/ASCII_Elevation_Data.doc) but when I do this to the original file and then import it will not create the resulting raster into a polygon, stating that "The environmental window is ignored"

Ideally, I need to add all the different environmental considerations to the ASCII file and then import it as a raster. This will allow me to analyse it and then create a polygon of the extent of the layer i am looking at.

Can anyone suggest a series of steps to overcome this and produce a raster and then a polygon?

  • 1
    What does the header look like - Does it have correct x&yllcorners? And do you know what spatial reference is needed?
    – gm70560
    Commented Jan 21, 2015 at 16:10

2 Answers 2


I suppose you did these 2 steps correctly:

1- calculate the statistics of the .asc file.

2- set the spatial reference of the .asc file.

I don't think you have to import your .asc files into a geodatabase except you need to do special analysis that is not possible in ArcGIS with asc file.

"when I do this to the original file and then import it will not create the resulting raster into a polygon,"

What do you mean by a polygon?

  • do you need a polygon that shows the extent of the raster?

  • answer: check Link

  • do you need polygons of the same pixel value (e.g. elevations) created from the raster?

  • answer: use "Raster to Polygon (Data management)" tool with you *.asc files.

  • Essentially, I am trying to create a file from the ASCII file that I can create a boundary around (predicted range edge). I think a polygon will create a ring around this area, but first I need to create the ASCII file into a file which can be manipulated. I have split the predicted occurrence into 5 values (0-100%), and from that I would like to have a neat edge, not a pixelated edge.
    – Mr Angus
    Commented Jan 26, 2015 at 1:04

If you were able to import your ascii file as an image, you already have a raster file. You should then check if the spatial reference is OK by adding another layer (e.g. open street map). If it is not well georeference, please provide the first lines of your ascii file otherwise there are too many possibilities for automatic or semi-automated georeferencing. Or you can use the georeferencing toolbar in ArcGIS to manually adjust your data to some reference layer.

This file can be converted to polygons using "raster to polygon" (in the conversion toolbox). However, this conversion is only possible if you have a valid raster of integer values. Therefore, you need to use one of the following spatial analyst tools (extension required) or make sure that your ascii file contains only integer values with

in the raster calculator(I use *100 to keep some precision as an example, but you know your data better : Int("yourrastername"*100)

using the reclassify tool to define some classes.

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