KDE in ArcGis 10.4 ; problem with the Reclassify tool and Raster to Polygon

[Živa Justinek]

Hey Colin,

I'm also fairly new to GIS and have gone through a huge part of this forum to find a solution. But couldn't. :( I've found your exact procedure how to estimate the home range through MCP and KDE and I followed both. While there has been absolutely no problem with MCP, I cannot make the KDE work.

I've done directly the Kernel density tool under Spatial analyst tools, because there is no barriers present. Then I extracted values to points and found the values to form 50% and 90% PVC. But when I wish to reclassify my kernel, it doesn't work. I tried restarting everything, changing values, etc...literally testing everthing. In the attachment you can see what was the error. The output name was not too long, nor had any spaces or similar.
I anyway tried to just put my kernel into polygon with the conversion tool, but there it is not even displayed as an input option!

I checked too many tutorial videos on youtube already and I am completely desperate. Thank you for your time in advance!

Cheers,

Živa

[GIS in Ecology]

Hi Ziva,

Thanks for your post. The RECLASSIFY tool can sometimes be a bit problematic to get working.

Looking at your error messages, there are two things that I would suggest trying.

First, your folder names have a couple of non-standard alphanumeric characters in them (the accent over the Z in your name, and then the hyphens - in the folder name diploma. This can cause problems with some GIS tools. To test whether this is causing a problem, create a new folder with a very simple name (like GISWork) directly on your C drive (so it has the address C:/GISWork) and try making your reclassified KDEs in this folder.

You can also try changing they way your KDE layer is displayed before opening the RECLASSIFY tool. To do this, right click on the name of your KDE data layer in the TABLE OF CONTENTS window and select PROPERTIES. In the LAYER PROPERTIES window, click on the SYMBOLOGY tab, and in this tab, set the symbology so that it displays the data layer as two discrete categories based on the ranges you want to use in your reclassification (i.e. 0 to your threshold value for one, and then your threshold value to the max value for the other). Once you have done this, close the LAYER PROPERTIES window and then open the RECLASSIFY tool. This should cause it to select your pre-set values and you can see if the tool runs by leaving the folder name and file name as the default values and clicking RUN to run the tool.

If neither of these works, look at the ranges of values you are using and look at whether any of them have numbers after the decimal point. If this is the case, you would need to check whether your computer is set up to use commas as the decimal separator, or decimal points. ArcGIS can have problems in recognising the correct decimal separator on computers where the default is a comma (as is the case in much of Europe). To see whether this could be causing the problem, try entering a value for the reclassification range that does not contain a decimal fraction and see if that works. If it does, it suggests that this is causing the problem. Unfortunately, the solution to this is to change how your computer is set up, and this can cause problems for other software and documents.

Hopefully, one of these will solve your problem, but if it doesn't, post back on this thread to let me know and I'll see what else I can suggest. Similarly, if you need any further explanations, or indeed if this solution works, post back on this thread to let others know what works for you.

Good luck.

All the best,

Colin

[Živa Justinek]

Colin, thank you for your swift response - you're really amazing!

Anyhow, I managed to find a combination of settings to make it work. It does not have a logical background solution, but somehow I have the polygons now. It's like rebirth. :)

What I did was, I exported data of the KDE raster file as a 'grid' file. Then, in the reclassify tool I didn't set the new value to 50/90 and other to no data, but rather excluded the whole range of points below the wanted value and created only one single class with the value of 1 which actually presented my PCV. Already in the first place, I did not understand why you suggested setting the value in the table to 50 or 90? Does is matter? As far as I understand, that's a sort of label only. Well, anyhow. :) I also checked the 'Change missing values to no data' box.
And on top, I let the stubborn ArcGis have his own name for the Reclass layer (did not rename it in my systematical way).

Does this make any sense? :)

If you have another minute, I would have one more question. I have a lot of sets of data...and I'm noticing that in the 90%PCV polygon (everything set as written above), occasionally I can find a point or even a few of them which belongs to this 90% outside of the actual polygon line. Is this normal and the edges of the polygon are broader than they would be without this lonely left out point or is there something wrong?

Thank you in advance!

Ziva