Constructing a pseudo node free network

• RivEX is capable of constructing a new river network without pseudo nodes. During this process the original dataset is not altered.

• The output of this process is a new Shapefile with the suffix "_Pseudo_Node_Free" and stored in the C:\RivEX\Output directory.

• The new Shapefile will honour polylineM and polylineZ features.  However RivEX does not recalibrate M values for a polylineM features.

• The option of constructing a new pseudo node free network is only available if you select identify pseudo nodes.

• Ticking the "Remove pseudo nodes from network" check box will cause the following message box to appear.  It is displayed to warn you that the new network will not have the attribution of the original network.

• Accept this box and click on Go!

• For large networks (20,000+ polylines) it will take several minutes to process the network. 

• There are two (of three) main stages for creating a pseudo node free network.  The first stage extracts out all polylines that do not have a node that could be a pseudo node. The second main stage is to process the remaining polylines by searching upstream and downstream combining polylines into single polylines.

• Due to the variety and complexity of river networks, RivEX has a built in "escape" clause.  If it gets into a loop and repeats itself 1000 times it will bail out reporting the ID number of the failing polyline.

• The process of creating a pseudo node free network means that polylines are merged into a single polyline.  To keep a logical consistency with ID numbering and attribution, RivEX drops all attributes from the original dataset and it is up to you to rebuild your attribution.  As a consequence of this, it is recommended that you quality control your network, remove pseudo nodes (if you need to), rebuild node layers and then attribute your network with stream order and link type.

• The image below demonstrates a pseudo node free network.

• The attribute table of the newly created pseudo node free river network will contain two new fields, PolylineID and Origin.  PolylineID is a new unique number given to each polyline and Origin is where the polyline has come from.  If it is given a value of "O" then it is simply a copy of the polyline from the original dataset where as "U" means it is a product of a union of 2 or more polylines as shown in the image below.