Introduction

KMLCENTERLINE2GRID creates a curvilinear grid based on an input KML centerline file. When deployed, this function behaves differently (and includes a seperate help).

Summary

This function fits continuously differentiable piece-wise cubic splines to the input centerline, determining the normal vectors at a spacing (ds) specified by the user. Then, the lateral spacing (dn) is used to contruct points on either side of the PCS centerline up to the specified half width (beta).

This function is especially handy for constructing 2-D computational and/or sampling grids along curved channels with roughly parallel banks.

Installation

1. To run from the source code, you will need Matlab, and the Mapping Toolbox.
2. Also required is the KML Toolbox, found on the Matlab FileExcange
3. Clone this repository using git:

• if you have a key associated with your github account git clone [email protected]:frank-engel-usgs/kmlcenterline2grid.git

• otherwise git clone https://github.com/frank-engel-usgs/kmlcenterline2grid.git

Usage

###Inputs

inputfile: KML file of the grid centerline
outputfile: name of the output file
ds: Desired spacing between point in the curvilinear grid in the along
centerline direction (streamwise)
dn: Desired spacing between point in the curvilinear grid perpendicular
to the centerline (cross-stream)
beta: Half width of the desired grid (half channel width)

###Outputs

centerline: Structure array containing the following fields
s:   Streamwise distance along curvilinear grid path
xn:   UTM East coordinates for each grid node
yn:   UTM North coordinates for each grid node
ds:   Streamwise grid node spacing
dn:   Cross-stream grid node spacing
beta: Cross-stream grid half width
KML file with the name outputfile containing the computational grid
CSV file (no header) with the coordinates of the the grid in UTM WGS84

###Examples Create a sampling grid for the Missuori River near St. Charles, saved as a KML file to be viewed in Google Earth The following code:

centerline = kmlcenterline2grid('Example.kml','TestOut',100,50,300)

Results in:

centerline = 

s: [1x62 double]
xn: [62x13 double]
yn: [62x13 double]
ds: 100
dn: 50
beta: 300

Tip: To create orthogonal transects, set dn = beta

Attribution

Original PCS curvature code by: Inci Guneralp (Texas A&M) Grid Production code by: Frank L. Engel, USGS