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QCoherent Software, LLC

 

Conflating Z Vales by Feature


About computing one or more Z values for the input geometry as a whole

The Summarize Z Values dialog allows you to customize how Z values are calculated for input geometry. The by feature option calculates summary values for all vertices and stores the result(s) in the attribute table in the output data set. Thus, this option can store more than one elevation statistic for each feature, but nothing is stored in the Z component of each vertex. A feature digitized using this method will have a value of zero stored in the feature file for Z if the feature file is 3D.

Since nothing is stored in the Z field of a feature vertex, you can use either 2D or 3D features. (This is the only Summarize Z option that allows you to use 2D features.)

Calculating Z values by feature computes one or more values for the entire input geometry. The Z value(s) that can be computed are the following:



Since this method stores values in the attribute table associated with the features, you must define the attributes. When you select this option, the LP360 Conflate Task dialog will display a field mapping table to the right of the Conflation Methods list. These fields correspond to the options you selected here in the Summarize Z dialog. For example, if you select only Mean Z, then the mapping table would contain only this value. The values on the left in the Property column represent the values that will be computed. The values in the Field column represent the name you must provide in the feature attribute table. For example, if you have defined a field in the attribute table called Average Z, then you would change the field value for the Property "MeanZ” to “Average Z”. You can use the default names to avoid this. However, you are sometimes faced with using pre-defined attribute schemas so this remapping is the way to address that situation.

An example of using the "by feature" option

Mean, Min and Max Z calculated for each building polygon  

How to Open the Summarize Z Values Dialog

The Calculate Z by Vertex option is selected on the Summarize Z Values dialog box. There are three situations in which you will encounter this dialog:

(1) When setting up an elevation conflaton task, you begin by using the Elevation Conflation/Classify dialog box, opened using the  button on the LP360 Classify toolbar. Once you select the Layer or Data Set and then the features (in the Fields drop-down) to use in the conflation, you will select a Conflation Method for each listed feature in the Data Types table.


To select the conflation method, click on the cell under Conflation Method in the table next to one of the listed features. Another drop-down list will allow you to select a conflation method.

 Select Summarize Z. The Summarize Z Values dialog will open.

 

(2)  When digitizing features in LP360, you will likely have the LP360 Digitize Breaklines toolbar open, and from this, you can manage conflation tasks using the Conflate Tasks Manager. (It opens using the button on the LP360 Digitize Breaklines toolbar.)

When you select a task in the Conflate Tasks Manager dialog box and then click the Edit Task button, the LP360 Conflate Task Dialog opens, allowing you to further define a conflation task, including the Conflation Method.

In the Conflation Method drop-down, select Summarize Z and then click the button. The Summarize Z Values dialog will open.

(3) When selecting "Summarize Z Values" from the Conflation Method drop-down list in the Conflation Point Cloud Task property page.

How to Calculate and Store Z in the Attribute Table

 
  1. Open the Summarize Z Values dialog box, as explained in the "How to Open the Summarize Z Values Dialog" section above.
  2. To calculate a summarized Z value and store the value in the Attribute table, select the computing one or more Z values for the input geometry as a whole option button.

  3. Next, select all of the Z values to calculate by feature.
  4. If you use the Mean, Minimum, or Maximum value to calculate Z, you will also need to select a spatial relationship. See Selecting a Spatial Relationship for more information.

  5. Enter a No Data Value assignment for features or vertices that cannot be assigned a Z value. See Assigning a No Data Value for more information.

  6. Select Treat as closed polylines.  

  7. Click OK.