ET Surface -  Raster functions performance and limitations

The performance of the raster functions of ET Surface depends on the specification of the computer (Processor & RAM). There are however several other factors that influence the performance depending on the function.  All function check at the beginning whether whether the memory available will be enough to complete the function. Some general considerations:

• Do not use smaller cell size than required for the task. The cell size defines how much memory will be needed and influences significantly on the performance of the functions. It is a good idea to calculate the approximate number of cells of the output raster - based on the extent of the output -  Number Cells = Width x Height / CellSize²

• If you are going to execute a function that requires a lot of resources

  • Close the unnecessary applications to free some memory.

  • Restart ArcMap with a new project.

  • Load only the data necessary for the function

  • Execute the function.

The table below tries to indicate the factors that influence the performance and the limitations in number of cells for each function. Common factors influencing the performance and keys used in the table.:

• Distribution of the input points - normally the more even the distribution - the better the performance - DP

• Number of input points  - NP

• Number of cells in the input raster - NCI

• Cell Size the smaller the cell size, the larger the output - CS

• Difference between the minimum and maximum weight for the cost functions - DW

• Contour Interval - CI

• Smoothing -SM

• Extent of the output - EO

All the limits below tested on standard Pentium PC with 2 Gigabytes of RAM

Indication for the limits in the table below - a raster that covers 100kilometers by 100kilometers with cell size of 20 meters will have 25,000,000 cells.

Performance depends on

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