Using multiple transition layers in gdistance (least cost analysis)

Dear all,

I have created shortest paths using slope with Tobler's (and others) cost
functions, but I'm wondering if anyone has used multiple transition layers
to create a more 'realistic' model?

I currently have a raster of rivers, with the rivers having a value of 1000
and the land as a value of 1. I would like to integrate this within the
model so as to block the travel through rivers.

I have found that I can do the following, which will define areas where
paths can go:


*rfac = asFactor(rivers == 0)rfactr <-  transition(rfac, "areas", 8)*

However, I'm not sure whether there needs to be a geocorrection after each
transition calculation, then multiplying the slope-transition layer and the
river-transition layer, or whether a single geocorrection should be done
after the two layers are multiplied together.

Any help, or links to where this has been done before would be appreciated.

Kind regards,
Joe

<http://www.avg.com/email-signature?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail>
Virus-free.
www.avg.com
<http://www.avg.com/email-signature?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail>
<#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2>