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GEOG585: Internet Mapping: Lab 6

Question 1

1. Given that McKinley County NM is contained within the following BBOX: -109.1, 34.5, -107.0, 35.4, answer the following questions:

  1. What is the aspect ratio of this geographic region?  2.33333
  2. What would be the height (in whole pixels) for a map image for this region that is 600 pixels wide? 257
  3. Formulate a WMS request that reflects the values determined in 1.1 and 1.2 above for the WMS service used above in the examples. Include in your answer both the actual WMS request and the returned map image. http://gstore.unm.edu/apps/rgis/datasets/97810/services/ogc/wms?VERSION=1.1.1&SERVICE=WMS&REQUEST=GetMap&BBOX=-109.1,34.5,-107,35.4&LAYERS=2007fe_35_county00&FORMAT=image/png&TRANSPARENT=TRUE&STYLES=&SRS=EPSG:4326&WIDTH=600&HEIGHT=257
    Image
  4. Formulate a WMS request for a 600x400 pixel map image that represents the full width of the defined geographic region, and is based upon the minimum Y value of 34.5 degrees North Latitude. Include in your answer both the WMS request and the returned map image.
    http://gstore.unm.edu/apps/rgis/datasets/97810/services/ogc/wms?VERSION=1.1.1&SERVICE=WMS&REQUEST=GetMap&BBOX=-109.1,34.5,-107,35.83&LAYERS=2007fe_35_county00&FORMAT=image/png&TRANSPARENT=TRUE&STYLES=&SRS=EPSG:4326&WIDTH=600&HEIGHT=400
    d

Question 2

2)  Given a WMS that is represented by the following GetCapabilities request, formulate individual GetMap requests for each of the following layers: bmng2km, bmng500mA1, landsat, and doqq05

http://edacwms.unm.edu/cgi-bin/mapfiles/edacimagery?SERVICE=WMS&VERSION=1.1.1&REQUEST=GetCapabilities

http://edacwms.unm.edu/cgi-bin/mapfiles/edacimagery?SERVICE=WMS&VERSION=1.1.1&REQUEST=GetMap&LAYERS=bmng2km&BBOX=-108,33.5,-102,39.5&FORMAT=image/png&STYLES=&SRS=EPSG:4326&WIDTH=308&HEIGHT=308

http://edacwms.unm.edu/cgi-bin/mapfiles/edacimagery?SERVICE=WMS&VERSION=1.1.1&REQUEST=GetMap&LAYERS=bmng500mA1&BBOX=-108.1,33.5,-107.1,34.5&FORMAT=image/png&STYLES=&SRS=EPSG:4326&WIDTH=298&HEIGHT=298

http://edacwms.unm.edu/cgi-bin/mapfiles/edacimagery?SERVICE=WMS&VERSION=1.1.1&REQUEST=GetMap&LAYERS=landsat&BBOX=-108.1,33.5,-107.1,34.5&FORMAT=image/png&STYLES=&SRS=EPSG:4326&WIDTH=1429&HEIGHT=1429

http://edacwms.unm.edu/cgi-bin/mapfiles/edacimagery?SERVICE=WMS&VERSION=1.1.1&REQUEST=GetMap&LAYERS=doqq05&BBOX=-108.1,35,-108,35.1&FORMAT=image/png&STYLES=&SRS=EPSG:4326&WIDTH=1964&HEIGHT=1964

  1. Which layers return map images that display image content? All at the proper scale
  2. Sometimes when WMS layers are accessed, there is a limit on the map scales for which the map image will be returned. If a request is submitted for a map scale that is outside the range specifed for a given layer, typically, a blank map image will be returned. From examining the information for these layers in the GetCapabilities XML document - which element in each layerʼs service metadata do you think provides information about the scales for which the layer will return map images containing data?  <ScaleHint>
  3. You can effectively change the scale of a map image by changing the pixel dimensions of the requested image. Which map images contain data for each of the following map image widths (remember to adjust the image height to match the BBOX of the request)
    1) 100 pixels bmng500mA1
    2) 1000 pixels Landsat, doqq05

Question 3

3) Below is a link to a KML file that includes a single GroundOverlay element that, in turn, contains a single Icon and href element that contains a WMS request (including all layers in the service in the “LAYERS” parameter) to the imagery service you worked with in question 2, above.

https://docs.google.com/leaf?id=0B631pWlrK6GGZTAxOGM4NTQtOTQyOS00NjU2LWJjN2MtZjc0OGFiOWZlZmQ4&hl=en

  1. Open the supplied KML file in Google Earth and enable it by clicking the checkbox next to its name in the “Temporary Places” pane on the left side of the user interface. Zoom in over several steps to the intersection of Interstate 25 and 40 in Albuquerque. What do you notice as you stop zooming?  Refreshes with scale dependant layer
  2. How does what you see relate to the scale dependencies that were highlighted in question 2 above? Each scale range brings in a new layer
  3. Open the KML file in a text editor (like Notepad). Using the original GroundOverlay element and its content as a template, create new KML files, one for each layer in the original, with each of the multiple layers in the original file being the only one included in the Layers parameter of the WMS request in the href element (remember to rename the GroundOverlay element so that they can be distinguished in the legend).  KML files: SW_KML.rar
  4. What happens when you add the KML file depicting bmng2km to Google Earth?  A nice raster overlay is added on top of google earths standard image of the southwest.
  5. What happens when you change (by editing the KML file, saving the change, and re-adding the file to Google Earth) the image format in the KML WMS to image/png? If there is a change in what you see, why do you think it happens?.  PNG looks good

Question 4

4) BONUS Question - What WMS parameter(s) are missing from the href element in the GroundOverlay in the KML? Why do you think it/they are missing?  SERVICE=WMS, BBOX.  GE is smart enough to calculate the extent of the region.