[R-sig-Geo] Using pixel image as spatstat's intensity surface

[Allar Haav]

Ah! Thank you! Exponenting the "model" truly fixed the problem as, 
indeed, the pixel image indeed stems from a multinomial logit model. I 
am not really sure why though, something to do with Poisson process 
probability function?

All the best,
Allar

On 23/07/2013 22:57, Rolf Turner wrote:
> This does not make a hell of a lot of sense to me.  Can you make your 
> data ("sites" and "model")
> available to me to experiment with and see what is going on?
>
> Basically if you think that "model" represents the underlying 
> intensity for "sites" then
>
>     X <- rpoispp(model)
>
> should bear at least a *vague* resemblance to "sites".   If you think 
> that "model" represents
> the reciprocal of the underlying intensity for "sites" then
>
>     recipMod <- eval.im(1/model)
>     Y <- rpoispp(recipMod)
>
> should yield a "Y" which bears at least a vague resemblance to 
> "sites".  If neither of these
> apply then it would appear that "model" has nothing to do with the 
> intensity underlying sites,
> and you shouldn't be using it.  Or perhaps some other transformation 
> of "model" is
> required.  Perhaps you need to use exp(model)?  This would apply if 
> "model" arises from
> the *linear* predictor of a loglinear model for the intensity.
>
>     cheers,
>
>         Rolf