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 Number of binary digits Equation
Number of possible values
Minimum Value
Maximum Value
1 (bit)
2^1 2 1
2^2 4 3
2^3 8 7
4 (nibble)
2^4 16 15 5
2^5 32 31 6
2^6 64 63
2^7
128
127
8 (byte)
2^8
256
255 9
2^9
512
511 10
2^10
1024
1023 12
2^12
2048
2047
2^15
32768
32767
16 (word)
2^16
65536
65535 20
2^20 24
2^24
2^31
2^32 48
2^48
2^64

4. Range of Computer Numbers
Bits
Name
Number of values / Precision
Minimum
Maximum
Uses
8-bit integer
Byte
256
255 RS
16-bit unsigned integer
Unsigned short
65536
65535
DEMs
16-bit signed integer
Signed short
-32767
32767
32-bit integer
Long integer
~4 billion
~ -2 billion
~2 billion
Counts, Categorical
32-bit float
Float
7-8
- ~ ~
Continuous
64-bit float
Double
14-15
- ~ ~

5. Performance By Type Type Calculations Queries Bytes
16-bit unsigned integer
Fast 2
16-bit signed integer
32-bit signed 4
32-bit float
Moderate
64-bit float 8
Date
Slow
7 and up
Strings
1 and up

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 10 12 15 16 Band 1 Y Dimension 1419 27 23
Band 2 18 22 30 29 21 25 32 34
Sample
Pixel: All the samples are coincident

8. Raster Resolutions Spatial Resolution: Spectral 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: Spectral (Number of Bands): Temporal:
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: µm
Number of Bands: 7
Temporal Resolution: 16 days
Image Size: 185 km X 172 km
Swath: 185 km
Programmable: yes

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