GDL - GNU Data Language / Discussion / Help: Does CONTOUR /OVERPLOT /FILL work on MAP

Hi,

I have a question about CONTOUR /FILL /OVERPLOT.

The following code works beautifully and generates color contour as I expected:

url='http://eosdap.hdfgroup.uiuc.edu:8080/opendap/data/NASAFILES/hdf4/AIRS.2002.08.01.L3.RetStd_H031.v4.0.21
.0.G06104133732.hdf'
fid = NCDF_OPEN(url)
vid = NCDF_VARID(fid, 'Temperature_MW_A')
NCDF_ATTGET, fid, vid, 'long_name', long_name
PRINT, long_name
NCDF_ATTGET, fid, vid, '_FillValue', fillvalue
PRINT, fillvalue
NCDF_VARGET, fid, vid, data

; Subset data.
data2D = data[*,*,11]
data2D=Reform(data2D)

; Process fill values, convert data that are equal to fillvalue to NaN
dataf=float(data2D)
fillvaluef = float(fillvalue(0))
idx=WHERE(dataf eq fillvaluef, cnt)
IF cnt GT 0 THEN dataf[idx] = !Values.F_NAN

vid = NCDF_VARID(fid, 'Longitude')
NCDF_VARGET, fid, vid, lon

vid = NCDF_VARID(fid, 'Latitude')
NCDF_VARGET, fid, vid, lat

levels=254
DEVICE
LOADCT, 33, NCOLORS=levels, BOTTOM=1
CONTOUR, dataf, lon, lat, /FILL, NLEVELS=levels, POSITION=[0.05, 0.06, 0.82, 0.80]

units = 'K'
XYOUTS, 0.5, 0.9, /NORMAL, url , CHARSIZE=1.3, ALIGNMENT=0.5
XYOUTS, 0.05, 0.86, /NORMAL, 'FIELD:Temperature_MW_A at TempPrsLvls=11', $
    CHARSIZE=1.25,  ALIGNMENT=0.0
XYOUTS, 0.94, 0.86, /NORMAL, 'UNIT:' + units, $ 
    CHARSIZE=1.25,  ALIGNMENT=1.0

However, if I add MAP_SET and /OVERPLOT on CONTOUR for the same code, it gives an error.

PLPLOT ERROR, ABORTING OPERATION
plfshade: shade_max must exceed shade_min, aborting operation

At the end, GDL shows only box grid and map continent.
Doesn't CONTOUR /FILL work with MAP_SET yet in GDL 0.9.4 with PLplot 5.9.11?

url='http://eosdap.hdfgroup.uiuc.edu:8080/opendap/data/NASAFILES/hdf4/AIRS.2002.08.01.L3.RetStd_H031.v4.0.21
.0.G06104133732.hdf'
fid = NCDF_OPEN(url)
vid = NCDF_VARID(fid, 'Temperature_MW_A')
NCDF_ATTGET, fid, vid, 'long_name', long_name
PRINT, long_name
NCDF_ATTGET, fid, vid, '_FillValue', fillvalue
PRINT, fillvalue
NCDF_VARGET, fid, vid, data

; Subset data.
data2D = data[*,*,11]
data2D=Reform(data2D)

; Process fill values, convert data that are equal to fillvalue to NaN
dataf=float(data2D)
fillvaluef = float(fillvalue(0))
idx=WHERE(dataf eq fillvaluef, cnt)
IF cnt GT 0 THEN dataf[idx] = !Values.F_NAN

vid = NCDF_VARID(fid, 'Longitude')
NCDF_VARGET, fid, vid, lon

vid = NCDF_VARID(fid, 'Latitude')
NCDF_VARGET, fid, vid, lat

levels=254
DEVICE
LOADCT, 33, NCOLORS=levels, BOTTOM=1
MAP_SET, /GRID, /CONTINENT, POSITION=[0.05, 0.06, 0.82, 0.80]
CONTOUR, dataf, lon, lat, /OVERPLOT, /FILL, NLEVELS=levels, POSITION=[0.05, 0.06, 0.82, 0.80]
units = 'K'
XYOUTS, 0.5, 0.9, /NORMAL, url , CHARSIZE=1.3, ALIGNMENT=0.5
XYOUTS, 0.05, 0.86, /NORMAL, 'FIELD:Temperature_MW_A at TempPrsLvls=11', $
    CHARSIZE=1.25,  ALIGNMENT=0.0
XYOUTS, 0.94, 0.86, /NORMAL, 'UNIT:' + units, $ 
    CHARSIZE=1.25,  ALIGNMENT=1.0
MAP_GRID, /BOX_AXES, COLOR=WHITE, /HIRES
MAP_CONTINENTS, COLOR=WHITE, /HIRES

Alain C. - 2014-01-16

Hi

thanks for the feedback, we learned a lot !
Do you really succeed to run in GDL:

url='http://eosdap.hdfgroup.uiuc.edu:8080/opendap/data/NASAFILES/hdf4/AIRS.2002.08.01.L3.RetStd_H031.v4.0.21.0.G06104133732.hdf'
fid = NCDF_OPEN(url)

If yes, please detailed the OS + netcdf version !
I tried on various recent Linux machines, without success up to now.
I read it is related to opendap, now available in netcdf 4.1+
Never tried before.

(I am trying to reproduce running you code)

Alain

PS: I am working on NetCDF-4 functionalities in GDL
since a week, I would really appreciate feedbacks
to test and improve the code (e.g. I have no example
for NCDF_UNLIMDIMSINQ)

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Alain C. - 2014-01-17

OK, I understood: I broke few days ago this DAP in netCDF trying to improve
the way NCDF_OPEN() checks files !

--> I will correct it ASAP (today)

--> I will add few extra tests cases !

thanks

Alain

PS: after that I will give a look to your question !

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giloo - 2014-01-17

Hi,
Thanks for this nice example that will be useful for me to test CONTOUR in the future.

I can reproduce your bug.
Actually several plotting routines in 0.9.4 behave better than in 0.9.3 but... are broken when using projections. We'll have to investigate/repair, this is known. Apparently CONTOUR not only ignores projection but destroys the projection information.

You could try to CONTOUR but with map already projected.
I have successfully done (but map_patch is terribly long with GDL):
MAP_SET, POSITION=[0.05, 0.06, 0.82, 0.80]
patched=map_patch(dataf,lon,lat)
CONTOUR, patched, POSITION=[0.05, 0.06, 0.82, 0.80],nlev=24 ; kills PROJ ^(
MAP_SET, POSITION=[0.05, 0.06, 0.82, 0.80],/noerase ; restore proj
MAP_CONTINENTS, COLOR=WHITE, /HIRES

I noticed also that MAP_PROJ_FORWARD hangs GDL. Another projection-related bug.

For Alain C.: I too succeed in loading the data with ncdf_open (version { 0.9.4 CVS Jan 5 2014 1388876400} on an up to date mageia3 distro).

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- Hyo-Kyung Lee - 2014-01-23
  
  Hi, Giloo!
  
  Thanks for the map_patch() technique. I tried it and I could plot data on the map. However, CONTOUR doesn't produce the desired filled color plot. Here are the images that I could get so far:
  
  http://hdfeos.org/examples/images/gdl/map.patch.gdl.png
  http://hdfeos.org/examples/images/gdl/map.patch2.gdl.png
  
  Compare it with the desired plot:
  
  http://hdfeos.org/examples/images/gdl/opendap.gdl.png
  
  Anyway, I've summarized my GDL experience here and you may want to check it out.
  
  http://hdfeos.org/software/gdl.php
  
  If you have a complete working code and a screenshot, please send it to eoshelp@hdfgroup.org. Thanks!
  
  If you would like to refer to this comment somewhere else in this project, copy and paste the following link:

giloo - 2014-01-23

Hi,
Actually I can reproduce your example. it was not using map_patch, i was wrong.
The problem is, since Contour 'ignores' (hopefully temporarily) the existence of a projection, you must map exactly the coordinates of the 2D contour image (vectors lon,lat) with the contours of continents.
just do:

MAP_SET, POSITION=[0.05, 0.06, 0.82, 0.8] ; set projection CONTOUR, dataf, lon, lat, /FILL, NLEVELS=levels, POSITION=[0.05, 0.06, 0.82, 0.80],/xst,/yst,xtickint=45,ytickint=30 ; contour kills projection info MAP_SET, POSITION=[0.05, 0.06, 0.82, 0.8],/noerase ; restore projection info MAP_CONTINENTS, COLOR=WHITE ; draw continents

I used loadct,39 for the attached plot, since loadct,33 plots the text in black with my configuration (?).

snapshot2.png
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- Hyo-Kyung Lee - 2014-01-24
  
  Thanks, giloo! This is awesome!
  
  I could get the same nice plot over map so I updated the GDL webpage with a new screenshot and code:
  
  http://hdfeos.org/software/gdl.php
  
  I put an acknowledgement in the complete sample code:
  
  http://hdfeos.org/examples/code/gdl/opendap.gdl
  
  If you'd like to see your real name and organization in the acknowledgement section or other acknowledgement statement, please feel free to contact me at eoshelp@hdfgroup.org. I really appreciate your help and support.
  
  p.s. I hope GDL can package map support as a built-in feature. Building from the source was too difficult and error-prone.
  
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Does CONTOUR /OVERPLOT /FILL work on MAP_SET?

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Does CONTOUR /OVERPLOT /FILL work on MAP_SET?

Does CONTOUR /OVERPLOT /FILL work on MAP_SET?

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Does CONTOUR /OVERPLOT /FILL work on MAP_SET?