1 / 13

Performance

Performance. Performance is fundamentally limited by: Size of data Where the data is stored Type of processing Processing software Hardware available. Real Performance Limitations. Rasters: Size of the data and number of files Points: Number of rows, number of size of attributes

rjohansson
Download Presentation

Performance

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Performance • Performance is fundamentally limited by: • Size of data • Where the data is stored • Type of processing • Processing software • Hardware available

  2. Real Performance Limitations • Rasters: Size of the data and number of files • Points: Number of rows, number of size of attributes • Network access, especially services • ArcGIS tools • Mistakes in processing • Hardware

  3. Size of Digital Values

  4. Range of Computer Numbers

  5. Performance By Type

  6. 4 Resolutions of Remote Sensing • Spatial: • X and Y resolution • Spectral: • Number of bands • Temporal: • Number of samples per time unit • Radiometric: • Number of bits or bytes per sample

  7. Raster Structure X Dimension Band 0 16 15 10 12 Band 1 23 27 14 19 Band 2 Y Dimension 29 30 18 22 34 32 21 25 Sample Pixel: All the samples are coincident

  8. Raster Resolutions • Spatial Resolution: • Width and height of each sample/pixel • Spectral Resolution: • Number of widths of the bands • Radiometric Resolution: • Number of bits per band • Temporal Resolution: • Number of rasters per time interval

  9. Raster Resolutions • Spatial: • 10 cm to 1 km • Spectral (Number of Bands): • 3 for photos, 7 for Landsat, for 256 MODIS • Temporal: • Daily for MODIS, 15 days for Landsat, every few years for SRTM • Radiometric (Sample Depth): • 8 bits=0 to 255 (256 shades)

  10. Raster Size Size in Bytes = Width of the area * Resolution * Height of the area * Resolution * Bytes per band * Number of bands * Number of Temporal Slices

  11. Landsat TM Scene • Sensor type: opto-mechanical • Spatial Resolution: 30 m (120 m - thermal) • Spectral Range: 0.45 - 12.5 µm • Number of Bands: 7 • Temporal Resolution: 16 days • Image Size: 185 km X 172 km • Swath: 185 km • Programmable: yes http://landsat.gsfc.nasa.gov/about/tm.html

  12. Improving Performance • It used to be storing the data was a major problem • Today, the problem is getting the computer processor “close” to the data

  13. Improving Performance • Resample rasters to the size desired • Clip rasters to the area of interest • Only use the bands required • Store or “cache” rasters to the computer doing the processing • Include performance evaluation as part of the modeling design

More Related