Subject: Marine Geospatial Ecology Tools (MGET) help
Text archives
| From: | Jana Jeglinski <> |
|---|---|
| To: | "" <> |
| Subject: | [mget-help] Problem with MGET "interpolate no data cells" tool |
| Date: | Tue, 20 May 2014 09:48:26 +0100 |
| Accept-language: | en-GB |
| Acceptlanguage: | en-GB |
Hello,
I came across an interesting situation using the fill NaNs in rasters tool
and it would be fantastic if you could point me to some help.
The purpose for using the tool is to fill empty cells in rasters of
environmental covariates such as chlorophyll concentration (Aqua Modis NPP
0.025 degrees acquired from coastwatch) with the general aim to extract
values of these covariates for GPS tracking data from sea lions. I am
particularly interested in filling empty cells along the coastline, because
the animals I study forage very coastally and the quite coarse resolution of
the covariate datatsets uses an equally coarse landmask, which leaves gaps of
at least one cell to the true coastline.
I had no problems running the tool but discovered that in some of my
covariate chlorophyll rasters negative values are produced for previously
empty cells. This of course is a major problem because an animal that foraged
in this cell would "prefer" a negative chlorophyll concentration. Do yo have
an idea how this can happen during the extrapolation process? Would you be
able to help me how to avoid this situation, while being able to fill in
empty cells? I have been playing around with different settings and methods -
reducing the number of connected NaNs to 6 and in some case to 2 helped, but
of course does not do the job of extrapolating the missing data along the
coastline. I also used spring, which was more successful (out of 12 rasters
where negative values were produced only one ended up with negatives), but
not 100%.
I am using MGET 0.8a50 with Arc GIS desktop 10.1, have installed Matlab and
have a spatial analyst license.
I hope I managed to explain my problem in enough detail. Thank you very much
for your response.
Kind regards,
Jana Jeglinski
Dr. Jana W E Jeglinski
University of Glasgow
Institute of Biodiversity, Animal Health
and Comparative Medicine
Graham Kerr Building, Rm 510
G12 8QQ, Scotland
Tel: +44 141 330 3560
University of Bielefeld
Galapagos Sea Lion Project
Department of Animal Behaviour
Morgenbreede 45
33615 Bielefeld
Germany
I came across an interesting situation using the fill NaNs in rasters tool
and it would be fantastic if you could point me to some help.
The purpose for using the tool is to fill empty cells in rasters of
environmental covariates such as chlorophyll concentration (Aqua Modis NPP
0.025 degrees acquired from coastwatch) with the general aim to extract
values of these covariates for GPS tracking data from sea lions. I am
particularly interested in filling empty cells along the coastline, because
the animals I study forage very coastally and the quite coarse resolution of
the covariate datatsets uses an equally coarse landmask, which leaves gaps of
at least one cell to the true coastline.
I had no problems running the tool but discovered that in some of my
covariate chlorophyll rasters negative values are produced for previously
empty cells. This of course is a major problem because an animal that foraged
in this cell would "prefer" a negative chlorophyll concentration. Do yo have
an idea how this can happen during the extrapolation process? Would you be
able to help me how to avoid this situation, while being able to fill in
empty cells? I have been playing around with different settings and methods -
reducing the number of connected NaNs to 6 and in some case to 2 helped, but
of course does not do the job of extrapolating the missing data along the
coastline. I also used spring, which was more successful (out of 12 rasters
where negative values were produced only one ended up with negatives), but
not 100%.
I am using MGET 0.8a50 with Arc GIS desktop 10.1, have installed Matlab and
have a spatial analyst license.
I hope I managed to explain my problem in enough detail. Thank you very much
for your response.
Kind regards,
Jana Jeglinski
Dr. Jana W E Jeglinski
University of Glasgow
Institute of Biodiversity, Animal Health
and Comparative Medicine
Graham Kerr Building, Rm 510
G12 8QQ, Scotland
Tel: +44 141 330 3560
University of Bielefeld
Galapagos Sea Lion Project
Department of Animal Behaviour
Morgenbreede 45
33615 Bielefeld
Germany
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