error message

[Husam El Alqamy]

I am trying to use the connectivity tool kit to workout connectivity and corridors in predicted distribution ranges that was produced using MAXENT. I tried to put my ASCII file in the specified box in HexMaps tab with the hexagon area specified as 1 but I had this error message in the output tab.

 

Rows: -1 Columns: 0 Hexagons: 0

Generating from source: C:\IBX_corid\Nubian_Ibex3.asc

Output = 0

Unexpected exception in HexMapGenerator

 

When I tried to play with the hexagon area as 10, 100, 500 I got the same error message. When I tried 0.05 for area the program gave the following message and crashed

 

Rows: -1 Columns: 0 Hexagons: 0

Generating from source: C:\IBX_corid\Nubian_Ibex3.asc

Output = 0

Resolution: 5156

Writing hexagon file: C:\IBX_corid\ibx_hab.hxn

 

Is there any restrictions regarding the projection of the ASCII file, should be projected or the program can proceed with Geographic ASCII? I wonder what I am doing wrong. My area is about 4000 Km. Sq and cell size is about 1.00 Km. sq. Hope to find help on the group.

Regards

 

Husam El Alqamy, B.Sc., M.Phil.

Protected Area Coordinator

Biodiversity Management Sector

Environment Agency - Abu Dhabi, UAE

Antelope Specialist Group - IUCN

 

[carlos]

I am pretty sure that geographic coordinates are not allowed (not a
true projection). Can you try projecting the data to eg, Albers and
see if the error persists? Thanks.

[carlos]

Alternately, can you post the header text from your .asc file?
such as
ncols 11754
nrows 9889
xllcorner 705227.125
yllcorner 1179968.125
cellsize 50
NODATA_value -9999

[Husam El Alqamy]

Thanks Carlos
Projecting the ASCII file into UTM R36N solved the problem. However, I am
still stumbling through using the interface. I went through exercise 1 to
get some taste of it but my work is essentially different as I don’t Have a
COST ASCII, I only have the habitat suitability prediction. I thought that a
combination of altitude and slope rasters could serve as cost factors but
the species I am working with is mountain specialist so these are not valid
ecologically. Could anybody discuss what to do in a situation where only
habitat prediction is available and I want to get an estimate connectivity
among these habitat patches.
Regards

Husam El Alqamy, B.Sc., M.Phil.
Protected Area Coordinator
Biodiversity Management Sector
Environment Agency - Abu Dhabi, UAE
Antelope Specialist Group - IUCN

[carlos]

With only habitat suitability information,
you can run either betweenness centrality or current flow betweenness
centrality, but not mincostflow. And if you just want to analyze a
linkage between two patches, you can run the subset version of each of
these.
I would start with betweenness centrality.
Create a graph file from your hxn file using the 'Distance
[Betweeness]' format in the graphs tab.
But depending on how your habitat data is scaled (is it a probability
(0-1), or a ranking (1-100)?), you may have to rescale it before
creating the hxn file. I often square the values (in GIS) for this
step.

[Husam El Alqamy]

Thank you very much Carlos for the help. My probabilities is 0-1. I applied
the methodology that you proposed and it worked but what after. I couldn’t
display the output of what I did as the produced output files had no header
with column names. I just would like to ask if you have or anybody on the
list a tutorial or examples that illustrate how to use the software
including how to display the output using GIS.

[Carlos Carroll]

There are tutorial files included with the download, and a (brief)
description in the manual on how to join the output files to the
shapefile. All the output files should have a header line of HEX_ID,
VALUE
Let me know if you have more questions. We'll work on expanding the
tutorial for the next release.