mbmosher's channel shows some the raster layers that I compiled for the echo::system project.
Find out more here:
http://ame2.asu.edu/projects/echoSystem/
Lessons Of Being Human
My Personal Transformations and Lessons
Theme and Variations
Wednesday, January 15, 2014
Wednesday, June 19, 2013
Saturday, October 29, 2011
Traverse Line With Multiple Vertices
Command Line Execute of Path Tracing Program
Way-point finding
algorithm
The 'path' is a multi-segment line, 'poly-line', each
segment is composed of a start and end vertices. The more detailed the path the
more segments are needed to describe the shape of the poly-line. The poly-line for the Echo::System project
was relatively coarse (in comparison to the 75881 meters that path traversed)
using 30 vertices (ie pairs of x and y coordinates); however, 30 vertices is adequate. The goal is to 1) render the current location on a map and 2) use the new coordinates to perform a
spatial query of a database, with a
100 meter buffer. The spatial query was an intersection of the geometry in the
database with a circle buffer around the way-point.
The Algorithm to find a 'way point' for any distance
along the path is a combination of the pythagorean theorem,
a line interpolation function, and a few if statements to handle the fringe
cases. The algorithm takes a distance
and returns the coordinates of the way-point, ie the current location. The way-point can then be rendered, after
scaling, in a graphic interface or the way-point is used, with-out scaling, to
query the spatial database.
All the vertices were captured by hand digitization in a
GIS (Geographic Information System).
Here, the vertices that are found in this report are accurate when used
in the projection system UTM 27 12N (The
1927 standard of projection, in central Arizona 12N. However, any means of capturing or simply
writing a set of coordinates would
work—depending of the application and subsequent utilization of the way point
geometry. For example, to simply render a moving object through a Cartesian coordinate system, one could simply write the coordinates of that system in two
arrays—one for x and one for y and then apply the algorithm iteratively to have
an object traverse the set of vertices.
**PYTHON CODE**
**Though this is python syntax, the algorithm and structure
of data is easy to read and simple to convert to any language.**
import math
import sys
"""THE X
AND Y ARRAY< UTM COORIDINATES NAD27 12N"""
XCOORD = [412289.298439,
412726.272491,412762.686995, 412981.174021, 421975.556587, 422011.971091,
421866.313074, 422011.971091,421793.484065, 421731.148716, 421811.604292,
421802.707074, 421724.811872, 421684.240552, 423213.649734, 429386.697708,
430136.355440, 430751.452127, 432353.690317, 433591.783463, 434028.757515,
435048.363636, 442985.698246, 451179.989048, 451088.439122, 450488.113466, ]
YCOORD = [3698314.413159,
3698277.998655, 3697622.537577, 3697404.050552, 3697404.050552, 3694873.242502,
3694509.097458, 3693926.465389, 3693198.175303, 3682258.321551, 3681768.668214,
3681288.218442, 3681146.205408, 3674025.938781, 3673133.783425, 3666978.075473,
3665894.790950, 3664813.069189, 3664194.022616, 3662701.027939, 3660916.717227,
3658731.846969, 3651541.523362, 3651428.170527, 3649901.843337, 3649790.545163,]
#needs length of line, and
distance
def getPercentPosition(d,
l):
p = d/l #percent
of line travelled
return p #returns
a fraction of distance/totalLength (ie .5 halfway)
# coordinates of segment
((a1,b1)(a2,b2)) and how far we are inbetween
def
getCoordinatesOnLine(a1, a2, b1, b2, percentPosition):
p = percentPosition
w1 = (a1 * (1-p)) + b1 * p #
for the x coordinate
w2 = (a2 * (1-p)) + b2 * p # for the y
coordinate
return w1, w2
# good ol' pythagorean,
length of line in 2 dimensions
def
getLengthOfLine(a1,a2,b1,b2):
l = math.sqrt(math.pow((b1-a1),2)+(math.pow((b2-a2),2)))
return l
#make an array for each of
the segment ((XCOOR,YCOOR)(XCOOR+1,YCOOR+1))
def buildLengthTable():
totalLength = 0.0 #total length of arcs:
for i in range(0, len(XCOORD)-1):
l = getLengthOfLine(XCOORD[i], YCOORD[i],
XCOORD[i+1], YCOORD[i+1])
segmentLength.append(l)
totalLength = l + totalLength
def
segmentByCount(distance):
distanceToTravelonSegment = distance
for segment in segmentLength: # go through each element in segmentLength[].
# if the distance to travel is less than the
first segment, then your done.
if distanceToTravelonSegment
# we've arrived at the segment
where we will stop.
break
# if the distance to travel is greater than
the current segment.
if distanceToTravelonSegment>segment:
# the segment is traveled, the
distanceToTravel is lessened.
distanceToTravelonSegment = distanceToTravelonSegment - segment
count = count + 1
return distanceToTravelonSegment, count
def main(distance):
distanceToTravel = sys.argv[1] # The argument provided by the caller
segmentLength = [] #
array of all the segment lengths
totalLength = 0.0 #
total length of all arcs (nice to know)
distanceToTravel= 0.0 #
the distance that will be traveled
w1 = 0.0 #
coordinates on line after distance traveled
w2 = 0.0 #
coordinates on line after distance traveled
count = 0
buildLengthTable()
distanceToTravel, count = segmentBYCount(distance)
positionOnline =
getPercentPosition(distanceToTravel,segmentLength[count])
w1, w2 = getCoordinatesOnLine(XCOORD[count],
YCOORD[count], XCOORD[count+1], YCOORD[count+1], positionOnline)
print "UTM coordinates: ", w1, w2
Friday, September 9, 2011
Monday, August 29, 2011
Echo::System
I'll be now reporting all of my Echo::System Project activity on this page.
The main site for Echo::System can be found here:http://www.echo-system.org/
The main site for Echo::System can be found here:http://www.echo-system.org/
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Purpose: Ecological Services
To promote
Biodiversity, Resilience, Complexity, feedback
In
Neighborhoods, Communities, Regions
For
Waste assimilation, recycling, reusing, economy, animal habitat, food production, carbon sequestering, water and land quaility
By
Investing in pre-existing systems, entrepreneurial methods, creating ecocentric communities
Biodiversity, Resilience, Complexity, feedback
In
Neighborhoods, Communities, Regions
For
Waste assimilation, recycling, reusing, economy, animal habitat, food production, carbon sequestering, water and land quaility
By
Investing in pre-existing systems, entrepreneurial methods, creating ecocentric communities