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wiki:exercise1a [2017/12/05 22:53] (current)
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 +====== Exercise 1a: View Landsat image and overlay vector ======
 +In this exercise the following tools will be used:
 +  * gdal/ogr tools: ogr2ogr, openev
  
 +Create a directory for this exercise:
 +
 +<code bash>
 +mkdir -p ${OUTPUTDIR}/​exercise1
 +</​code>​
 +
 +Open the Landsat image with an image viewer (e.g., openev)
 +
 +<code bash>
 +openev -h ${LANDSATDIR}/​${LANDSATIMG}
 +</​code>​
 +
 +__Select different band settings (false colour images)__
 +
 +consult web page with landsat bands for different thematic band settings
 +
 +<note tip>​Natural (true) colour for Landsat image: R=band 3(red), G=band 2 (green), B=band1 (blue)</​note>​
 +
 +__Zoom in on particular area of interest__
 +
 +  * method 1: use + button
 +  * method 2: control button + drag window
 +  * method 3: control button + left mouse button
 +
 +__Zoom out__
 +
 +  * method 1: use - button
 +  * method 2: control button + right mouse button
 +  * method 3: use fit all layers button (square box with arrow in each corners)
 +
 +__Reproject water vector to epsg:3035 (ETRS89:​LAEA)__
 +
 +<code bash>
 +ogr2ogr -t_srs epsg:3035 ${OUTPUTDIR}/​exercise1/​cornwall_water_3035.shp ${VECTORDIR}/​cornwall_water.shp
 +</​code>​
 +
 +__Create vector with forested areas by selecting forest from natural vector and reprojecting to epsg:3035 (ETRS89:​LAEA)__
 +
 +<code bash>
 +ogr2ogr -t_srs epsg:3035 -where "TYPE in ('​forest'​)"​ ${OUTPUTDIR}/​exercise1/​cornwall_forest_3035.shp ${VECTORDIR}/​cornwall_natural.shp
 +</​code>​
 +
 +__Open forest vector in openev on top of landsat raster image__
 +
 +Question: can you distinguish forest from other vegetated areas?
 +
 +Question: can you easily distinguish forest from inland water?
 +
 +__Select the standard false colour composite for Landsat imagery__
 +
 +Consult web pages
 +
 +  * http://​web.pdx.edu/​~emch/​ip1/​bandcombinations.html
 +  * http://​zulu.ssc.nasa.gov/​mrsid/​tutorial/​Landsat%20Tutorial-V1.html
 +
 +<note tip>​Standard false colour settings for Landsat imagery: R=band 4(NIR), G=band 3(red), B=band2(green)</​note>​
 +
 +<note warning>​Do not forget to enhance raster after loading new band combination using the button with horizontal line</​note>​
 +
 +Question: What does vegetation look like in this false colour image, why?
 +
 +Questions: What about water and forest now?
wiki/exercise1a.txt ยท Last modified: 2017/12/05 22:53 (external edit)