Stratified sampling using a grid

• RivEX+ can generate a grid over your network and sample a fixed number of points per grid cell.  This is stratified sampling.  Such output could feed into further river analysis or compliment a survey strategy.

• You have a variety of options that can influence (bias) the selection process and it is important that you understand these. Click here to review these options.

• The output is written to the default directory C:\RivEX\output.  Each point stored will contain the following information:

• Unique ID
• ID of intersecting polyline
• XY coordinates
• % along polyline

• You must first set the layer and polyline ID field.

• Then set the cell size in meters and enter the number of times you want to sample within each grid cell.  You have the option to keep the grid generated by RivEX+ otherwise it is destroyed when processing has completed.

• RivEX+ adds a field to the grid layer which records the actual number of points generated per grid cell.  This is useful for quality control, so it is recommended that you keep the grid after sampling.