Category Archives: tutorial

Enhanced spectral ratio on classic client

We slightly changed the functionality of the spectrum and spectral ratio buttons on www.planetserver.eu. The following explanation is just for visualization and does not have scientific significance.

The spectral ratio button (1/2) now acquires the y spectrum of the x/y ratio. This is reflected on the map as a blue point:
p1
The user can only draw one point at the time, when clicking a new location the old point is removed. This will load the spectrum into memory for later use to calculate the x/y spectral ratio.

If you now click on the spectrum button and start clicking spectra on the map the blue point remains visible but the divisor ‘y’ spectrum has been removed from the diagram. Instead you see the red and green spectra in the diagram. These are both spectral ratios: red/blue and green/blue:
p2

You can now also load a library spectrum together with spectral ratios:
p3

If you now would go back to the spectral ratio button you can change the blue point. When you then return to the Spectrum button the next spectral ratios you click use the new blue point spectrum for the ratio:
p4

In summary: this enhancement allows 1) the drawing of more than one spectral ratio and 2) combining spectral ratio’s and library spectra in the diagram.

Related console additions:

  • resetspectra() =>  reset the spectrum diagram to the initial state after loading the CRISM data. This will become a reset button in the GUI.
  • chooseratio(lon,lat) => choose y of the x/y spectral ratio (console version of the spectral ratio button)
    OR:
    chooseratio() and before pressing enter move the mouse to the location you would like to use as the to-be-ratio’ed spectrum.
  • addspectrum(lon,lat) => select a spectrum and show in the diagram (console version of the spectrum button). When you have selected the to-be-ratio’ed spectrum before then the x/y ratio is shown in the diagram.
    OR:
    addspectrum() and before pressing enter move the mouse to the location you would like to have a ratio.
  • noratio() => a console implementation for turning ratio off. It removes the blue point drawn with the spectral ratio button. When you then add new spectra they are not ratio’ed anymore. But the previous ratio’ed spectra are still shown.

 

Export GeoTiff from PlanetServer

 GeoTiff Export from web client

PlanetServer can also export the screen in GeoTiff format, in order to exchange data and images with Desktop GIS systems and alike.

One should point the client towards a certain CRISM observation/data product, either interactively from http://planetserver.eu selecting a certain region or directly.

e.g.

http://planetserver.jacobs-university.de/?productid=HRL0000B63A_07_IF181S_TRR3

geotiff-1

The “Save for GIS” option should be ticked in the lower right corner of the console

geotiff-2

image[2]

the selection of the filename can be done interactively on the console:

WCPS>filename = "geotiff-olindex2.tif"
geotiff-olindex2.tif
WCPS> image(sp.olindex2)

geotiff-3

and a GeoTiff file called “geotiff-olindex.tif” is created (see Console in-depth)

The resulting GeoTiff, from gdalinfo, returns, e.g.


Driver: GTiff/GeoTIFF
Files: geotiff-olindex2.tif
Size is 420, 580
Coordinate System is `'
Origin = (2435019.832500000018626,-1195241.430099999997765)
Pixel Size = (36.000000000000000,-36.000000000000000)
Image Structure Metadata:
INTERLEAVE=BAND
Corner Coordinates:
Upper Left ( 2435019.833,-1195241.430)
Lower Left ( 2435019.833,-1216121.430)
Upper Right ( 2450139.833,-1195241.430)
Lower Right ( 2450139.833,-1216121.430)
Center ( 2442579.833,-1205681.430)
Band 1 Block=420x19 Type=Byte, ColorInterp=Gray
NoData Value=0

The Coordinate Reference System for GeoTiff files generated by PlanetServer is an Equirectangular:

Expressed as proj4:
+proj=eqc +lat_ts=0 +lat_0=0 +lon_0=0 +x_0=0 +y_0=0 +a=3396190 +b=3396190 +units=m +no_defs

Expressed as ESRI .prj:
PROJCS["Mars Equicylindrical clon=0",GEOGCS["GCS_Mars_2000_Sphere",DATUM["D_Mars_2000_Sphere",SPHEROID["Mars_2000_Sphere_IAU_IAG",3396190.0,0.0]],PRIMEM["Reference_Meridian",0.0],UNIT["Degree",0.0174532925199433]],PROJECTION["Equidistant_Cylindrical"],PARAMETER["False_Easting",0.0],PARAMETER["False_Northing",0.0],PARAMETER["Central_Meridian",0.0],PARAMETER["Standard_Parallel_1",0.0],UNIT["Meter",1.0]]

Expressed as Petascope CRS:

http://kahlua.eecs.jacobs-university.de:8080/def/crs/PS/0/2/

This applies to bands, or indices, band depths or any results obtained from WCPS calculations through the console.

PlanetServer 101

PlanetServer 101: basics

Planetserver’s stable web client (WebGUI) basic functionalities are listed and briefly explained below

Main Interface

The main interface is a pan & zoom full screen map with an upper toolbar

Toolbar (left portion)  toolbar-left

Toolbar (right portion), containing several buttons (see below) toolbar-right

Buttons

The first buttons that might provide info and help are:

@ - provides access to further sources of information (including this blog)

? – opens the tutorial PDF

Once a user pans over an area and selects a certain footprint (orange = unselected, blue = selected), a dialog for choosing the spectral range appears.

crism-choice

After that the main analysis set of widgets is visualized:

screen-crism

Analytical and query dialogs are then available

Dialogs/widgets

Each dialog/widget will have its own (or combined) in-depth blog post describing functionalities.

Table of Contents

It gives access to the selected data granule and each of its bands, including grayscale, RGB combinations

toc

Diagrams

Provide spectral graphing capabilities, histogram, spectral library visualisation, etc.

diagrams

Console

It allows spectral calculations, band queries, and other functions.

console

More info

For more info, please consult the PlanetServer PDF tutorial.

Also, a screencast (and eventual more to come will be added) is available from the EarthServer Vimeo page.