GOAL AND BACKGROUND
The goal of this lab was to learn how to create breaklines within ArcMap using LAS data, to use conflation to constrain downward slopes in rivers, and to enforce breaklines for hydro-flattening of water bodies.
METHODS
The LP360 extension in ArcMap was used for breakline creation. LiDAR data for Eau Claire was used for this section. First, the LAS data was added to ArcMap and displayed using the TIN surface. A ground filter was used to only display ground points. This was necessary so the edges of the river bank were shown instead of vegetation. First, the outline of the river was created, followed by a centerline of the river used to ensure a downward slope.
These shapefiles were brought into LP360. The breakline for the outline of the river was enforced. Then, the river-flattening tool was run, using the river bank shapefile and the river centerline shapefile.
Hydro-flattening was also performed on the Lake County data that the previous labs have used. There was no need to create breaklines for this as they were given, and no rivers in the data meant simpler hydro-flattening could be used. The breaklines were enforced and DTM and contour images were created.
RESULTS
Shown below is the final product in the creation of the centerline and riverbank shapefiles for the Eau Claire data.
Shown below is part of the table showing the constrained Z values along the centerline. The M value is how much the Z was adjusted to keep the river continuously downstream.
Shown below is the final result of the hydro-flattening in the Eau Claire data. Changes in elevation along the river are continuously downward as it flows downstream.
Next, the result from hydro-flattening in the Lake County data is shown. The simple ponds were flattened to be a single elevation.
A contour map of a section of the Lake County data was also created, shown below. It is overlaid on the NAIP imagery of the area.
SOURCES
Data obtained from Cyril Wilson for use in 358 LiDAR course.
