Environmental layers priority
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xavi rayo
Nov 21, 2017, 12:22:33 AM11/21/17
to Maxent
I'm tryin to model the habitat for posidonia oceanica in an smal region where I have several environmental layers like backscatter, bathymetry, aspect, slope an rugosity. I would like the model to use a primary enviropnemtal layer, the backscatter, as I'm working in an area with much diferrences betweenn slope or bathymetry. Is there a way to priorize a layer against the others. When I run the model, it apperars to use mostly the bathymetry, although there are important differences also in the backscatter. Maybe there is something I'm doing wrong or that I don't understand.
Thank you very much for your help!
MaxentNoob
Feb 8, 2018, 9:43:19 PM2/8/18
to Maxent
Don't use aspect. It is a circular variable. Catastrophic in particular if you project to a different resolution or coordinate reference system later.
Think about it. What is the mean angle of 360 and 0? Does it represent the original data in a meaningful way? Not at all.
Also consider that 0 and 360 both perfectly point to north and what that might do with your estimation of coefficients.
Simply transform with cosinus and sinus for easterness and northerness. You might call the latter southerness if you multiply it by -1.
In this case both layers are associated with more light (given you are north of the equator).
Cheers
Think about it. What is the mean angle of 360 and 0? Does it represent the original data in a meaningful way? Not at all.
Also consider that 0 and 360 both perfectly point to north and what that might do with your estimation of coefficients.
Simply transform with cosinus and sinus for easterness and northerness. You might call the latter southerness if you multiply it by -1.
In this case both layers are associated with more light (given you are north of the equator).
Cheers
Neftalí Sillero
Feb 9, 2018, 6:16:11 AM2/9/18
to max...@googlegroups.com
The easiest way to use aspect is to transform degrees to radians.
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Neftalí Sillero
Assistant Researcher
https://sites.google.com/site/neftalisillero/
https://scholar.google.pt/citations?user=yJHOX7IAAAAJ&hl=en
http://na2re.ismai.pt/
neftali...@gmail.com
CICGE: Centro de Investigação em Ciências Geo-Espaciais
Assistant Researcher
https://sites.google.com/site/neftalisillero/
https://scholar.google.pt/citations?user=yJHOX7IAAAAJ&hl=en
http://na2re.ismai.pt/
neftali...@gmail.com
CICGE: Centro de Investigação em Ciências Geo-Espaciais
Faculdade de Ciências da Universidade do Porto
Observatório Astronómico Prof. Manuel de Barros
Alameda do Monte da Virgem
4430-146 Vila Nova de Gaia, Portugal
Life is too short to eat bad chocolate
Observatório Astronómico Prof. Manuel de Barros
Alameda do Monte da Virgem
4430-146 Vila Nova de Gaia, Portugal
Life is too short to eat bad chocolate
Rainer Wunderlich
Feb 9, 2018, 7:04:24 AM2/9/18
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How is a transformation to radians helping here? The circularity of the variable remains totally unaffected when moving from degrees to radians. North can be represented by either 0 or 6.283. What point am I missing?
Cheers
On 9 Feb 2018 19:16, "Neftalí Sillero" <neftali...@gmail.com> wrote:
The easiest way to use aspect is to transform degrees to radians.
On Fri, 9 Feb 2018 at 02:43 MaxentNoob <rainer.w...@gmail.com> wrote:
Don't use aspect. It is a circular variable. Catastrophic in particular if you project to a different resolution or coordinate reference system later.--
Think about it. What is the mean angle of 360 and 0? Does it represent the original data in a meaningful way? Not at all.
Also consider that 0 and 360 both perfectly point to north and what that might do with your estimation of coefficients.
Simply transform with cosinus and sinus for easterness and northerness. You might call the latter southerness if you multiply it by -1.
In this case both layers are associated with more light (given you are north of the equator).
Cheers
On Tuesday, 21 November 2017 13:22:33 UTC+8, xavi rayo wrote:Hi!
I'm tryin to model the habitat for posidonia oceanica in an smal region where I have several environmental layers like backscatter, bathymetry, aspect, slope an rugosity. I would like the model to use a primary enviropnemtal layer, the backscatter, as I'm working in an area with much diferrences betweenn slope or bathymetry. Is there a way to priorize a layer against the others. When I run the model, it apperars to use mostly the bathymetry, although there are important differences also in the backscatter. Maybe there is something I'm doing wrong or that I don't understand.Thank you very much for your help!
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--Neftalí Sillero
Assistant Researcher
https://sites.google.com/site/neftalisillero/
https://scholar.google.pt/citations?user=yJHOX7IAAAAJ&hl=en
http://na2re.ismai.pt/
neftali...@gmail.com
CICGE: Centro de Investigação em Ciências Geo-EspaciaisFaculdade de Ciências da Universidade do Porto
Observatório Astronómico Prof. Manuel de Barros
Alameda do Monte da Virgem
4430-146 Vila Nova de Gaia, Portugal
Life is too short to eat bad chocolate
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Neftalí Sillero
Feb 12, 2018, 2:19:22 PM2/12/18
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Dear Rainer,
You are completely right about radians. They have the same problem than degrees. Sorry for the confusion.
Cheers
On Fri, 9 Feb 2018 at 12:04 Rainer Wunderlich <rainer.w...@gmail.com> wrote:
How is a transformation to radians helping here? The circularity of the variable remains totally unaffected when moving from degrees to radians. North can be represented by either 0 or 6.283. What point am I missing?CheersOn 9 Feb 2018 19:16, "Neftalí Sillero" <neftali...@gmail.com> wrote:
The easiest way to use aspect is to transform degrees to radians.
On Fri, 9 Feb 2018 at 02:43 MaxentNoob <rainer.w...@gmail.com> wrote:
Don't use aspect. It is a circular variable. Catastrophic in particular if you project to a different resolution or coordinate reference system later.--
Think about it. What is the mean angle of 360 and 0? Does it represent the original data in a meaningful way? Not at all.
Also consider that 0 and 360 both perfectly point to north and what that might do with your estimation of coefficients.
Simply transform with cosinus and sinus for easterness and northerness. You might call the latter southerness if you multiply it by -1.
In this case both layers are associated with more light (given you are north of the equator).
Cheers
On Tuesday, 21 November 2017 13:22:33 UTC+8, xavi rayo wrote:Hi!
I'm tryin to model the habitat for posidonia oceanica in an smal region where I have several environmental layers like backscatter, bathymetry, aspect, slope an rugosity. I would like the model to use a primary enviropnemtal layer, the backscatter, as I'm working in an area with much diferrences betweenn slope or bathymetry. Is there a way to priorize a layer against the others. When I run the model, it apperars to use mostly the bathymetry, although there are important differences also in the backscatter. Maybe there is something I'm doing wrong or that I don't understand.Thank you very much for your help!
You received this message because you are subscribed to the Google Groups "Maxent" group.
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----Neftalí Sillero
Assistant Researcher
https://sites.google.com/site/neftalisillero/
https://scholar.google.pt/citations?user=yJHOX7IAAAAJ&hl=en
http://na2re.ismai.pt/
neftali...@gmail.com
CICGE: Centro de Investigação em Ciências Geo-EspaciaisFaculdade de Ciências da Universidade do Porto
Observatório Astronómico Prof. Manuel de Barros
Alameda do Monte da Virgem
4430-146 Vila Nova de Gaia, Portugal
Life is too short to eat bad chocolate
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Francisco Amorim
Feb 12, 2018, 3:20:25 PM2/12/18
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You can always decompose aspect into northness and eastness using the cosine and sine functions. That way aspect will be decomposed into two linear variables each ranging -1:1.
Cheers
Em 12/02/2018 19:19, "Neftalí Sillero" <neftali...@gmail.com> escreveu:
Dear Rainer,You are completely right about radians. They have the same problem than degrees. Sorry for the confusion.Cheers
On Fri, 9 Feb 2018 at 12:04 Rainer Wunderlich <rainer.w...@gmail.com> wrote:
How is a transformation to radians helping here? The circularity of the variable remains totally unaffected when moving from degrees to radians. North can be represented by either 0 or 6.283. What point am I missing?CheersOn 9 Feb 2018 19:16, "Neftalí Sillero" <neftali...@gmail.com> wrote:
The easiest way to use aspect is to transform degrees to radians.
On Fri, 9 Feb 2018 at 02:43 MaxentNoob <rainer.w...@gmail.com> wrote:
Don't use aspect. It is a circular variable. Catastrophic in particular if you project to a different resolution or coordinate reference system later.--
Think about it. What is the mean angle of 360 and 0? Does it represent the original data in a meaningful way? Not at all.
Also consider that 0 and 360 both perfectly point to north and what that might do with your estimation of coefficients.
Simply transform with cosinus and sinus for easterness and northerness. You might call the latter southerness if you multiply it by -1.
In this case both layers are associated with more light (given you are north of the equator).
Cheers
On Tuesday, 21 November 2017 13:22:33 UTC+8, xavi rayo wrote:Hi!
I'm tryin to model the habitat for posidonia oceanica in an smal region where I have several environmental layers like backscatter, bathymetry, aspect, slope an rugosity. I would like the model to use a primary enviropnemtal layer, the backscatter, as I'm working in an area with much diferrences betweenn slope or bathymetry. Is there a way to priorize a layer against the others. When I run the model, it apperars to use mostly the bathymetry, although there are important differences also in the backscatter. Maybe there is something I'm doing wrong or that I don't understand.Thank you very much for your help!
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----Neftalí Sillero
Assistant Researcher
https://sites.google.com/site/neftalisillero/
https://scholar.google.pt/citations?user=yJHOX7IAAAAJ&hl=en
http://na2re.ismai.pt/
neftali...@gmail.com
CICGE: Centro de Investigação em Ciências Geo-EspaciaisFaculdade de Ciências da Universidade do Porto
Observatório Astronómico Prof. Manuel de Barros
Alameda do Monte da Virgem
4430-146 Vila Nova de Gaia, Portugal
Life is too short to eat bad chocolate
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----Neftalí Sillero
Assistant Researcher
https://sites.google.com/site/neftalisillero/
https://scholar.google.pt/citations?user=yJHOX7IAAAAJ&hl=en
http://na2re.ismai.pt/
neftali...@gmail.com
CICGE: Centro de Investigação em Ciências Geo-EspaciaisFaculdade de Ciências da Universidade do Porto
Observatório Astronómico Prof. Manuel de Barros
Alameda do Monte da Virgem
4430-146 Vila Nova de Gaia, Portugal
Life is too short to eat bad chocolate
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