Difference between revisions of "Tarsier tutorial: Raster data"
From CCoWS Wiki
(New page: == What are raster data? == Raster data are gridded data such as images and gridded maps of landscape properties such as elevation. The grid is typically two-dimensional, with the dimensi...) |
|||
| Line 14: | Line 14: | ||
== Obtaining raster data == | == Obtaining raster data == | ||
| − | Raster data are widely available on the web. | + | Raster data are widely available on the web. |
| − | # ... | + | === Example: Topography of Kauai === |
| + | |||
| + | ==== Obtain a digital elevation model for a portion of the USA - Kauai ==== | ||
| + | |||
| + | # Visit National Elevation Dataset (NED): http://ned.usgs.gov/ | ||
| + | # Navigate to Seamless Data Distribution System (SDDS): http://seamless.usgs.gov/ | ||
| + | # Select USA | ||
| + | # Zoom to Hawaiian Islands | ||
| + | # Zoom to Kauai - the northernmost island | ||
| + | # Click 'Download' on far right | ||
| + | # Select '[[SRTM]] Finished 3 arc sec' i.e. the coarest data available, since we just want a quick look | ||
| + | # Select 'Download' tool on far left | ||
| + | # Use tool to define the smallest rectangle that includes the entire island | ||
| + | # Click 'Download' in pop-up window that appears | ||
| + | # Save zip to local machine and extract to folder | ||
| + | # The folder should now contain an Arc GRID coverage - a bunch of files requiring ArcGIS software to open | ||
| + | |||
| + | ==== Convert Arc GRID file format to Arc '''ASCII''' GRID format === | ||
| + | |||
| + | Tarsier can't import native Arc GRID files. But it '''can''' import Arc ASCII GRID files that have been exported from Arc format using ArcGIS. | ||
| + | |||
| + | # Open ArcMap | ||
| + | # Add layer - your Arc GRID raster | ||
== Importing raster data into Tarsier format == | == Importing raster data into Tarsier format == | ||
Revision as of 14:50, 11 February 2009
Contents
What are raster data?
Raster data are gridded data such as images and gridded maps of landscape properties such as elevation. The grid is typically two-dimensional, with the dimensions representing coordinates such as latitutde and longitude.
Raster data and vector data are the most fundamental types of data used to represent landscapes.
Examples of raster data include:
- Maps of elevation (digital elevation models, DEMs)
- Maps of bathymetry
- Satellite images
- Aereal photos
- Maps of land cover (also often represented as vector data)
Obtaining raster data
Raster data are widely available on the web.
Example: Topography of Kauai
Obtain a digital elevation model for a portion of the USA - Kauai
- Visit National Elevation Dataset (NED): http://ned.usgs.gov/
- Navigate to Seamless Data Distribution System (SDDS): http://seamless.usgs.gov/
- Select USA
- Zoom to Hawaiian Islands
- Zoom to Kauai - the northernmost island
- Click 'Download' on far right
- Select 'SRTM Finished 3 arc sec' i.e. the coarest data available, since we just want a quick look
- Select 'Download' tool on far left
- Use tool to define the smallest rectangle that includes the entire island
- Click 'Download' in pop-up window that appears
- Save zip to local machine and extract to folder
- The folder should now contain an Arc GRID coverage - a bunch of files requiring ArcGIS software to open
= Convert Arc GRID file format to Arc ASCII GRID format
Tarsier can't import native Arc GRID files. But it can import Arc ASCII GRID files that have been exported from Arc format using ArcGIS.
- Open ArcMap
- Add layer - your Arc GRID raster
Importing raster data into Tarsier format
...
Viewing raster data
...
