The longest extent of anything as measured from end to end

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12
votes
4answers
2k views

Looking for a pythonic way to calculate the length of a WKT linestring

I was quite unsatisfied with Calculating Length of Linestrings in WGS84 in Miles. It kept me wondering if there is a more convenient, Pythonic way to calculate the length of a WKT linestring according ...
9
votes
2answers
633 views

POSTGIS get the max length of the polygon and the average width

I have in postgis a polygon type table. I need to calculate automatically the maximum length of the polygon: And the second one is the average width: I am doubting rigth now if this is possible ...
8
votes
1answer
421 views

Is there a best practice for the length of fields?

At my work have inherited several shapefiles that originate from MapInfo that I am bringing into a new project in QGIS. I have the opportunity to change the column names, add and subtract columns and ...
6
votes
1answer
3k views

How to measure length of line accurately?

In postgis 1.5 for the below given query the answer is 1540651.62674101 meters , SELECT ST_Length(ST_GeomFromText('LINESTRING(77.83042478941326 9.98463896136159,78.03469506809812 23.90398909552571 )'...
6
votes
2answers
1k views

How to create line with exact same length over and over again?

I need to draw 30 meter lines in specific places. Ctrl+l is too annoying to do everytime. Is there a easy way to define specific same length for a line that I need to draw many times?
6
votes
1answer
10k views

Calculating line segment lengths within polygon using ArcGIS Desktop?

I have a layer with line segments and a layer of polygons (in this case, buffers around points). I need to create a new field for each polygon that contains the total length of all line segments ...
6
votes
1answer
437 views

Permanently setting polygon/polyline segment length using ArcGIS Desktop?

I'm trying to create a several hundred polygons in ArcGIS 10, each of which may have up to several hundred vertices. For consistency sake I would like each line segment in these polygons to be of a ...
5
votes
2answers
5k views

Length of a degree: where do the terms in this formula come from?

Online calculators such as http://www.csgnetwork.com/degreelenllavcalc.html (view page source) use the below formulas to get meters per degree. I understand in general how distance per degree varies ...
5
votes
1answer
4k views

What units are shape_length in?

When generating polylines from a series of points, I used "Points to Line" tool. From this, Arc generates a polyline feature class, which includes the attribute shape_length. What units are these ...
5
votes
3answers
5k views

How to create a rectangle polygon with set lengths in QGIS?

I have a search area i want to outline. and i need it to be 1km by 2km. is it possible to achieve this in QGIS. I can create a rectangle polygon but only guess the lengths.
5
votes
3answers
3k views

Finding line length while editing in QGIS?

I am using QGIS. I would like to know if there is any way during the editing phase of a vector (line or polygon) to know the length of the line (total and partial) that is being created?
5
votes
1answer
796 views

How to emulate a specific vector grid in QGIS?

I would like to analyze data included in a pdf file. The file contains information on characteristics of 16km grid cells for a specific study area. The file also includes a map displaying the grid. I ...
4
votes
2answers
2k views

What is the unit the shapely length attribute?

I'm doing a very simple calculation of the length of a polyline using shapely: from shapely.geometry import LineString ... xy_list = [map(float,e) for e in xy_intm] line = LineString(xy_list) s = '%...
4
votes
1answer
159 views

Measurement not correct in QGIS 1.8

I have a SHP file of sub-areas of U.S. counties (roughly about the size of a Census tract) that I've reprojected into a 'true distance' projection (World Equidistant Cylindrical) in QGIS 1.8. However, ...
4
votes
2answers
1k views

Using Calculate Field (Data Management) tool to calculate 3D Length in ArcGIS 10.1

I'm relatively new to the world of model builder and scripting, so it's likely there is a very simple solution to the question I've been trying to figure out. I'm trying to create a tool that takes ...
4
votes
1answer
833 views

What's the unit of measurements produced by “sum line lengths”?

My goal is to find the total length of roads per county for a particular state. You would think there would be a simple government spreadsheet with this information in it.... I cannot figure out how ...
3
votes
3answers
854 views

Why is sum of st_length() of segments 20% too big?

I'm running a query to return the total length of some bike paths, from OpenStreetMap. Compared to the known actual length of these paths, they're all a bit too big - something like 10-30%. I know it ...
3
votes
3answers
8k views

Polyline length calculation in ArcGIS 10/VB script

I used to run this length calc on my data in ArcGIS 8 and 9, and now it don't work in ArcGIS10. Can you tell me what I have done wrong? Dim dbllength as double Dim pcurve as icurve Set Pcurve = [...
3
votes
3answers
308 views

How to calculate path length of each point from the start using arcpy?

As shown in the picture below I would like to calculate the path length of each point from the start. Can anyone give me some help in writing this in python for ArcGIS?
3
votes
3answers
2k views

How to Calculate length of polyline geometry for several tables in PostGIS?

PostGIS database contains several geometry (polyline) tables (with names "D1_r", "D2_r", "D3_r"). I calculate length for one "postgis layer" use request: SELECT sum(ST_Length_Spheroid(the_geom,'...
3
votes
3answers
935 views

ArcGIS Surface Length Tool equivalent in FME?

I am trying to calculate the 3D length of a line. I currently have a rather complex and cumbersome model built in ArcGIS ModelBuilder that uses a tool called "Surface Length". I was wondering if ...
3
votes
1answer
415 views

Measuring polyline lengths running through a raster - is this possible?

I have a reclassified raster layer with 4 values and a vector layer of polylines. I would like to discover the length of the lines running through each raster value, or the percentage of the lines ...
3
votes
1answer
998 views

Problem about converting raster to polyline and calculating total length

I have raster file of line segment. I need to convert it to line and get the distance of that line. How can i do using Python and ArcGIS 10? I have tried with GIS tools Convert Raster to Polyline but ...
3
votes
0answers
30 views

Loop distance point pyQgis

I have a .shp of lines where I'm able to calculate the sum of segments length but I'm trying to put a point at a given distance in meters. The problem is it puts a point at every segment. When I give ...
3
votes
0answers
561 views

How to convert length in Decimal degrees to meters programmatically?

I'm new to qgis and I want to find the length of some roads in a map. So I used the following code, from shapely.wkb import loads def getLength(): layer = qgis.utils.iface.mapCanvas().currentLayer()...
3
votes
0answers
1k views

How to get turn angle, line orientation and line length in ArcMap 9.3.1?

I am mapping and analysing animal movements using arcgis 9.3.1 along with Hawthorne Beyer's GME, and am trying to utilise the correlated random walk commands, but in order to do this I need to find ...
2
votes
1answer
296 views

Calculating the length of the network lines inside polygon in QGIS 2.10.1

I am working with 2 datasets: delineations of the neighbourhoods traffic network. This is how they look: I would like to calculate the length of the roads per neighbourhood (polygon). As you ...
2
votes
2answers
99 views

Flow Mapper wrong line length calculation

I'm finding some trouble with the length calculation in the Flow Mapper plugin. As you can see in the picture below the length of the 2 lines C001-C021 = 4233.7986... C001-C009 = 6069.3053... is ...
2
votes
1answer
137 views

Tag for calculating way length in osm2pgsql?

There is a special tag 'way_area' in osm2pgsql creating a database column that stores the area of polygon features. So is there something like this for calculation of length of line objects?
2
votes
1answer
120 views

How to examine length of vector lines in qgis/grass?

I have vector layer of lines. How can I examine length of lines?
2
votes
2answers
50 views

QGIS - How to determine the length of a KML line tracing

I have a KML file which contains a line feature representing the passage of an Optical Fiber connecting two cities. I can trace them nicely in QGIS and OpenStreetMap. I would just like to know how ...
2
votes
1answer
128 views

Get LineString length in meters (Python, GEODjango)

In a Django model, I have a LineString field which holds GPS coordinates of a street route. I know that I the .length holds the length of the LineString, but I don't know what unit the returned value ...
2
votes
1answer
57 views

QGIS polyline length calculation [closed]

I meet a problem while I try to calculate the length of a polyline in QGIS in the attribute table. I created a new column with the function "$length" inside (type: real, 10 digits and 3 digits of ...
2
votes
1answer
244 views

Line calculation from KML file

I am a beginner in QGIS 2 and Mac OSx Mountain Lion I need to get line length in meters for different gps waypoints. 1 I import kml file to create a new vector shape (this works fine). The projection ...
2
votes
1answer
176 views

Line feature, Merge and Dissolve

I have a layer with several polygons and a layer with line above these polygons. Its like a map and a road network on it. I have to find out the length of line in each polygon. I used the intersect ...
2
votes
0answers
52 views

Splitting polygon features at specific widths using ArcGIS for Desktop?

I have a group of islands and I need to divide them into different segments based on feature width at several locations. There are four values for width (50m, 100m, 200m, and 300m) which I need to ...
2
votes
0answers
144 views

How do I accurately measure a gps track over a long distance?

I am measuring the length of the Continental Divide Trail that goes from the Mexican border to the Canadian border. I have a .gpx file of the entire route in NAD83 with tracks about every 50 meters. I'...
2
votes
0answers
128 views

How to add column to attribute table using field calculator with $length function?

I used the following code to add a separate column to the attribute table with the length of features. from PyQt4.QtCore import QVariant from qgis.core import QgsField, QgsExpression, QgsFeature vl....
2
votes
0answers
519 views

FME - calculating distance to points along a line

I am new to FME, and trying to get my head around what should be pretty straightforward issues, but I find myself going around in circles Basically I want to determine the distance (chainage) to a ...
2
votes
1answer
292 views

Sum line length with clip intersect? [closed]

SELECT sum(st_length(st_intersection(POLY.geom, LINE.geom))) AS sum_line_length... Is this function OK to calculate the sum of lines length? Wonder if it do the clip line where one line go from one ...
1
vote
2answers
527 views

How to create a new column to store the length of a linestring in postgis?

I am working with pgRouting, following this nice guide:A Beginner’s Guide to pgRouting I am now in this step:Calculating shortest routes, with these codes below SELECT * FROM shortest_path(' SELECT ...
1
vote
2answers
3k views

Calculating sum of geometric length of shapefile in ArcGIS Desktop?

I have a shapefile with lots of line routes. I projected it and calculated the length using calculate geometry. How can I get the sum of all these routes in ArcGIS Desktop?
1
vote
2answers
178 views

Check shape orientation

I have a shapefile with many minimum bounding box (envelope) polygons and I need to find out, if the boxes are rather landscape or portrait format. (See pic below, one of the selected boxes should be ...
1
vote
1answer
428 views

Distance Between Two Points vs Length of Linestring

So I have two points that I want to calculate the distance between. If I use: SELECT ST_Distance_Spheroid(point_a, point_b, 'SPHEROID["GRS 1980",6378137,298.257222101]') / 1000 FROM ( ...
1
vote
2answers
1k views

Qgis - need to draw exact lines (mtrs) with fixed angle

I use GIS 1.8. I have the need to be able to draw exact lines and shapes on a bing map. (This is to project a yet to be build greenhous project on a map to show what i would look like). I have ...
1
vote
1answer
39 views

FME Segment Line with To/From Distance Values from Excel?

I have a large road network with some basic attributes like ROAD NAME, ROAD TYPE, LENGTH. Each road has been segmented but these segments are wrong for the new schema. I have successfully (mostly!) ...
1
vote
1answer
74 views

Create a line from an array and measure its length with PostGIS (ST_MakeLine, ST_Length)

do I understand it correctly that it is possible to create a line out of an array with the function ST_MakeLine()? I would like to create a line from several points (more than two) and then calculate ...
1
vote
2answers
239 views

How to separate polygons within layer and measure line through each polygon?

I have 3 layers of polygons, each layer with multiple polygons spatially separated, although the layer only counts it as 1 polygon. I have a layer with a line going through these polygons. What is ...
1
vote
1answer
310 views

Calculating field length in certain directions (raster)

Currently I'm working on winderosion. For my purpose I like to calculate the length of agricultural fields in certain wind direction. I would like to do it for raster. To be more precise: I have ...
1
vote
1answer
321 views

Problem of linear records with zero shape length and no geometry in attribute table

I am working with a bicycle and pedestrian facility file geodatabase in ArcMap. I noticed a some of the records in the shapefiles/feature classes have a shape length of zero in the shape length ...