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 ...
7
votes
2answers
171 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 ...
6
votes
1answer
2k 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
829 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
353 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
2k 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
991 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
2k views

How to find line length in QGIS while editing?

I am using QGIS (before, I used ArcView). 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 ...
5
votes
1answer
660 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
1k 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
147 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
3answers
4k 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.
4
votes
2answers
852 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
6k views

How do i calculate line segment lengths within a polygon?

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 ...
3
votes
3answers
605 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
5k 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
144 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
1k 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 ...
3
votes
3answers
813 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 Model Builder that uses a tool called "Surface Length". I was wondering if ...
3
votes
1answer
513 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
1answer
689 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
291 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 = ...
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
2answers
86 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
105 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
73 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
1answer
241 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 ...
2
votes
1answer
204 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
143 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
71 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. ...
2
votes
0answers
92 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 ...
2
votes
0answers
313 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
254 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
2k 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
65 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
253 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
729 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
2answers
102 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
191 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 ...
1
vote
1answer
40 views

How to get correct lengths when switching from GCS to PCS?

I'm working on ArcMap 10 and need to get the lenghts (in meters) of the segments composing my line feature class. GCS of the line is WGS_1984. Extent of this data should be: Left 11.236520 dd, Right ...
1
vote
1answer
79 views

How to change the attribute length of an existing field afterwards

I already have about 100 values in a field in QGIS. I set it to 50 characters because I was thinking that would be enough. But that was wrong. I need more space in the column. But there is no way to ...
1
vote
1answer
160 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
132 views

How to split/divide linestrings of larger lengths in postgis

I want to split/divide linestrings in my data. I have roads data and I want to have every road segment having length not more than 250 meter. Check the shape length of this particular line feature. ...
1
vote
1answer
345 views

3D and 2D lengths of lines in ArcGIS

I have a 2D road segment and convert it into 3D using a raster in ARCGIS 9.3. So, what i see is that the length of 3D road segment is still the same as the 2D road. How can this be? As due to ...
1
vote
0answers
34 views

Drawing features with specific dimensions in ArcGIS [closed]

I am having some issues drawing transect lines in ArcGIS. I need to create some lines that have specific lengths (20m and 30m). My Map units are set to 'meters' and coordinate system is NAD UTM 10. ...
1
vote
0answers
64 views

Deriving length values from GPX files in QGIS

I’m missing something real obvious and I apologize for revisiting a topic addressed in several Q&A’s here. I’m an experienced GIS user (not programmer) who’s new to QGIS (can’t afford Arc in ...
1
vote
0answers
68 views

Flow length analysis only shows pixel value, how to get length?

When I create a flow length analysis, and use identify tool on a cell in the layer, it just shows "stretched value" and "pixel value" I don't understand how it's supposed to show length. I'm using ...
1
vote
0answers
158 views

Length difference between Google Earth and ArcGIS for Desktop?

I have drawn a complex path with multiple vertices in Google Earth (GE) Pro and its measurement property is shown as being 2,460 nm. It is located East of Australia. If i import this KML into ArcGIS ...
1
vote
0answers
31 views

QGIS (2.0.1): Field calculator for length not working - values way too high

Same problem as another thread: Field Calculator returning incorrect length and area values Trying to calculate length of a line shapefile, and field calculator is returning values that are way too ...
1
vote
1answer
174 views

How to calculate highway lengths using QGIS? [closed]

I need to create a network of highways in 8 states of the USA. Eventually, I need their length, the speed and if possible average daily traffic volume, I don't know how to extract this information. ...