Re: Doubts about truncated values and pinchpoints

[John Gallo]

Hi,

For starters, best practice is to run pinchpoint mapper with the same truncation vcalue that you ran linkage pathways.  So, run it for 200,000, not 5,000 . Also, it looks like 2002017 resistance surface is such that you shold try a larger truncation, like 400,000 so the pinchpoints are not quite so narrow.  Unless you have an ecological reason for choosing 200,000.

Pinchpoint mapper runs circuitscape (circuit theory) within the footprint of the linkages.

Good luck!

John

John Gallo, Ph.D.
Senior Scientist
Conservation Biology Institute
136 SW Washington Avenue, Suite 202
Corvallis, OR 97333
Remote Office: Inglenook, CA

Phone: 707.962.9078
Twitter: @johnagallo

Updates: Action Research Newsletter

On Thu, Aug 20, 2020 at 6:37 PM epo...@gmail.com <epo...@gmail.com> wrote:

Hello, I hope you're all well and safe.
I'd like to know a little bit about Linkage Pathways' truncated values and how it works.
as I am looking to analyse the variation in time of these cost weighted distance areas but they have a different maximum cost weigted distance, so I intend to truncate the area to 200km.
I would also like to know a little more about the operation or analysis of pinchpoint mapper, or some metric or effective way to analyze the variation in time of these maps.

I am enclosing pictures of my results and would appreciate your feedback.
Thank you very much.

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[Li Xiaoxue]

Hello Dr. Gallo,
I am waiting for your help,I successfully ran the Linkage mapper on my projects，afterwards I ran the Pinchpoint mapper again without the Centrality option, and I did not get an error messages, However, the map it created (Linkage_current_adjacentPairs_10k) looked strange，and the current value didn’t look continuous.
I have attached a few screen shots to put it all into context.
Pinchpoint results (Linkage_current_adjacentPairs_10k).
Any thoughts?
Thank you so much,
Lee

[John Gallo]

Hello Lee,

This is possibly a symbology issue.  What is the value of the yellow pixels in the boxes?  It is possible that they are 0, but are being mapped as "low"

If no, we can go from there.

Thanks,

John

John Gallo, Ph.D.
Senior Scientist
Conservation Biology Institute
136 SW Washington Avenue, Suite 202
Corvallis, OR 97333
Remote Office: Inglenook, CA

Phone: 707.962.9078
Twitter: @johnagallo

Updates: Action Research Newsletter

To view this discussion on the web visit https://groups.google.com/d/msgid/linkage-mapper/6e4b133d-f0a9-4b67-93ec-7af9dd0c0272n%40googlegroups.com.

[Li Xiaoxue]

Hello Dr. Gallo，

I am sorry for my thoughtlessness, I tried to take the solution you provided and then got the new map(Figure 1), the current value In this new map looked discontinuous compared to the example diagram(Figure 3).

I suspect it is related to the resistance raster,do you have other ideas?

Thank you so much,

Lee

 Figure 1.original map                                           Figure 2                                                                  Figure 3

[John Gallo]

Hi Lee,

I'm assuming you meant Figure 2, not Figure 1. And it appears that you Figure 2 is an intermediate output of a run that is using surprising parameter values. 

To lessen the traffic on the list, please email me off list if you want to get to the bottom of all this.

If so, please email me with the methods you are using and if the analyses for Figure 2 and Figure 3 use the same input data.

Thank you,

John

John Gallo, Ph.D.
Senior Scientist
Conservation Biology Institute
136 SW Washington Avenue, Suite 202
Corvallis, OR 97333
Remote Office: Inglenook, CA

Phone: 707.962.9078
Twitter: @johnagallo

Updates: Action Research Newsletter

To view this discussion on the web visit https://groups.google.com/d/msgid/linkage-mapper/5b3bd6bb-2ffc-4102-ba88-b39e01154affn%40googlegroups.com.