Example Workflow: 3. On the Review dialog, click on the Properties button for the Coordinate system. The Coordinate System Properties dialog appears.

Transcription

1 Calculating LRS Measures for Linear Data Crossing the Road Network The following GeoMedia Transportation workflow might be used as a means to calculate LRS measure values where another linear feature crosses LRS network. Requirements: GeoMedia Professional, GeoMedia Transportation Manager and a valid LRS network that passes GeoMedia Transportation s LRS Validation command. Overview: In this workflow the following steps will be used to calculate LRS measure values on intersection markers for where rivers overlap the LRS network: Review Coordinate System of the LRS Spatial Intersection of LRS with Rivers Functional Attributes to: o expand collections o filter for true point geometries o Calculate X and Y Event Conversion for Coordinate Events Example Workflow: Review Coordinate System of the LRS: It will be very important to know the exact coordinate system parameters for the LRS. Coordinate system parameters can be easily referenced in a Coordinate System (.csf) File. 1. Select Manage Data tab > Features command. 2. Highlight the LRS feature on the Feature Class Definition dialog click on the Review button. 3. On the Review dialog, click on the Properties button for the Coordinate system. The Coordinate System Properties dialog appears. 4. Click on the Storage Space tab and review the unit of measure which will be expressed as meter. (See graphic below). We will use this value later when creating our Functional Expressions for X and Y. Page 1 of 8

2 5. Make a note of the unit of measure. 6. On the Coordinate System Properties dialog use the Save As to save to a coordinate system (.csf) file to some location such as C:\GeoWorkSpaces. We will reference the LRS coordinate system file later. 7. Close the dialogs after saving the coordinate system file. Page 2 of 8

3 Spatial Intersection 1. Select Analysis tab > Spatial Intersection. 2. Select the LRS feature class as the first (top level) Features in item (see graphic below). Note: The spatial intersection command compares 2 feature classes. By design the spatial intersection command performs its comparisons using the coordinate system of the first feature selected. 3. Set Overlap as the spatial operator. 4. Select the Rivers feature as the second (lower level) Features in item. 5. Set the Output Query name as: Q1 Spatial Isec LRS Overlap Rivers 6. Select OK to run the Spatial Intersection analysis. Note: Results of a spatial intersection query can result in points and/or lines when comparing 2 linear feature classes. Additionally, the results can be collections (multiple, disconnected graphics that highlight as one geometry record). We ll use the Functional Attributes command to filter out just the point intersections and expand any possible collections. Functional Attributes 1. Select Analysis tab > Functional Attributes command. 2. As input, expand the Queries section and select the Q1 spatial intersection query created in the last step. 3. Use the New button to build the following expressions: FA_Points FILTERPOINT(GEOMETRIES(Input.IntersectionGeometry)) FA_X X(Output.FA_Points, ProjectedMeas, Meter) FA_Y Y(Output.FA_Points, ProjectedMeas, Meter) Page 3 of 8

4 Note: When creating the X and Y expressions we can specify the desired unit of measure. It s important to define the expression using the unit of measure defined under the Storage Space tab of the coordinate system of the LRS feature. Recall we reviewed the unit earlier when saving the coordinate system file. If you are in doubt, you can review the coordinate system (.csf) file previously save/created. The Storage Space tab is typically expressed as some unit of meter. If the value is fractional then your unit of measure may be Survey Foot or Foot or some other unit. Appropriate units of measure can be found in the Constants category. 4. Name the output query, Q2 FA Event Points. LRS Event Conversion A very important aspect of the spatial intersection command is that each spatial intersection result carries the attributes of both features. In our case this means that each spatial intersection point has attributes from both the LRS (including the LRS key) and the River (for example the river name). 1. Select LRS tab > Conversion The LRS Event Conversion dialog appears. 2. Define the LRS feature, the LRS model and use the Properties button to define the Properties (see graphic below for example settings, your field names will be different of course). Page 4 of 8

5 3. Set the Event feature as the Q2 FA Event Points query previously created (see graphic below). 4. Optionally use the Attributes button to Unselect All then select only the attributes desired. Be sure to keep the NLF ID from the LRS feature as well as the Functional Attribute (FA) calculated attributes (see graphic below) Page 5 of 8

6 5. Click on the Event feature Properties button (see graphic below). Set the Event type as Point Set the Event reference type as Coordinate Set the primary key field(s). Set the Measure fields using the previously functional based x and y attributes. Set the Coordinate tolerance to 1.0 Use the Browse button to set the Event coordinate system. Browse for the coordinate system (.csf) file created previously that represents the LRS coordinate system. Page 6 of 8

7 6. Click OK 7. Set the Output to name as: Q3 River Crossing Events 8. Set the Output properties to Measure. Page 7 of 8

8 9. Click OK to generate calculate the measure values from the coordinate values. The Status1 column can be used for sorting to review any potential problems. If no measure values were calculated then most likely the unit of measure used in the functional attribute calculation for X and Y (see as FA_X and FA_Y attribute fields) is not in the unit defined by the coordinate system file previously loaded for the Event Coordinate system. An interesting aspect of this workflow is that the query results should be dynamic. If the road network (LRS) or the river geometry is modified, then each of the queries, including the measure values will be recalculated to reflect the changes in geometry(s). Adding Q3 to the legend should now show Measure values representing the LRS measure locations on the network where the intersection is located. Page 8 of 8