HyperNiche Slices

[Katie Blauvelt]

Hello,

I was wondering if there is a way to manually choose the value of each slice in the 3D slice graphs in HyperNiche.

Thank you for your time,

Katie Blauvelt

[Bruce McCune]

Katie, There is a way to control this somewhat, but ultimately it depends on the range of the values for the variable being sliced. It's good to pursue this! I think that slicing a 3D surface is a great way to show interactions among the predictors.

Let's say the variable ranges from 0 to 10, but you only want to show slices for 0, 1, 5 and 10. First select 11 slices, which would give you a slice for each integer from 0 to 10. Then click on the "plot multiple slices" button in the toolbar. Hold Ctrl key and click on 0, 1, 5, and 10, then click OK.

If the range of your variable isn't nice and neat, as in this example, you can choose a large number of slices and an appropriate number of decimal places for the legend so that you can select slices close to what you want.

Hope this helps,
Bruce McCune

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[Gottfried Jetschke]

Hi Bruce,

I wanted to produce a prediction map based on a particular model in HyperNiche. The program read my Ascii files (tile 16 from WorldClim variables) without any problems in the format of 3600 rows x 3600 columns (which can be seen as header in any text editor).

During calculation, the software also produced no error message, but the resulting text file stated that "GIS input grid has 600 rows and 600 columns".  The statistics given was also based on these 360.000 points. The output file had "ncols 3600, nrows 3600" in it's header, but could not be read by my Quantum GIS.

What could be the error? Do you have any specification of the structure of the input Ascii grid files available?

All the best,

Gottfried

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Gottfried Jetschke
Institute of Ecology
University of Jena
Dornburger Strasse 159 
D-07743 Jena, Germany
Phone: (+49) 3641 949420
Fax:     (+49) 3641 949402
e-mail: b...@uni-jena.de
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[Bruce McCune]

Hi Gottfried,

It sounds like the input files have an unexpected format that is somehow corrupting the output grid.  The Help system built into HyperNiche has a small example of the ascii grid format, reproduced below. I suggest looking at the header lines of each your input grids. If one of the grids is smaller (600 x 600 in this case), then the output grid will be limited to 600 x 600. But still, that shouldn't make the output grid unreadable.

One of the pickiest aspects of the *.asc format is that the numerical data in the header lines must start in column 15 for each line. In the example below, position the cursor at the first letter, then arrow right 14 characters (including spaces). This should position the cursor right before the first number (5 in this case). If for some reason the "3600" in an input file was positioned one character to the left, it would be read as "600".

If you don't see an obvious problem with the input files, please send the HyperNiche result file to me, along with the first six lines of the output grid. Let's do this outside the group to reduce email clutter.  You can email the problem using the technical help address for HyperNiche (Help | Technical Support) and forwarding this dialog. Once we figure out what is wrong, we can report what we found to the group.

Bruce McCune

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GIS Grid Files
HyperNiche reads and writes grids of data in ascii format (plain text files). This file format, with default extension *.asc, is imported and exported by ArcGIS, Arcview, ArcInfo, and other GIS software. The format of this file follows strict rules detailed in the ESRI documentation. Two examples are given below.

The grid below is a tiny example of a grid exported by ArcView and imported by HyperNiche. It specifies elevations in a map grid with 5 rows and 5 columns. The missing data value , called the NODATA_value in the standard *.asc format is -9999.

ncols         5
nrows         4
xllcorner     549397.1875
yllcorner     4888911
cellsize      10
NODATA_value  -9999
-9999 -9999 800 -9999 -9999
-9999 1000 1200 1050 -9999
1200 1200 1060 1300 1000
-9999 1000 1100 1100 1000

[Gottfried Jetschke]

Hi Bruce,

thanks for your suggestion. This immediately solved my problem.

When I converted BIL files into ASCII files with Quantum GIS, the ASCII files produced the first numerical data at position 14. This explains why HyperNiche read only 600 x 600 cells (instead of 3600 x 3600) and why it read 0 x 0 cells from a smaller 600 x 600 file.

It is strange to see that often people do understand the conceptual background of their model and applied operations, but become desperate because of a "simple" technical problem, like the format of a text file.

Again thanks for your help ...

Gottfried

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