Where features overlap

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3
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1answer
68 views

Verifying the number of times a line crosses other lines

I have a series of lines that represent streams. I have a stream line and two flowpath lines in one feature class and two banklines in another feature class. Total of five lines. I then have a feature ...
0
votes
0answers
35 views

Intersecting Overlapping Polygons Individually in ArcGIS

Map Layers: -Census Tract Shape File w/Population Data -Set of Store Locations with 5 Mile Buffers (Significant Overlap Between Buffers) I have create feature layers for both and I am trying to ...
3
votes
1answer
128 views

How do I figure out the longitude and latitude coordinates necessary to create a circular 1 mile radius around one location?

How do I figure out the longitude and latitude coordinates necessary to create a circular 1 mile radius around one location? I don't mind how many coordinates that takes. For instance: Latitude = ...
0
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0answers
60 views

Using M 'Measure' value in SQL Server 2008

MS Sql Server 2008 geometry type supports adding Z and M values to geometry objects, including linestrings. However, I cannot find any way to make use of these values, since methods such as ...
0
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0answers
22 views

Method of extracting the intersecting areas of multiple overlapping polygons (5) and classifying intersects based on spatially joined points

I have concave hulls surrounding clusters of data points which has led me to a lot of overlap and fuzzy boundaries. I am attempting to intersect the overlapping areas but have a minimum of 5 different ...
1
vote
0answers
55 views

How to Simulate Venn Diagram of Buffers using QGIS?

For the sake of simplicity, suppose I have only 2 points on one layer. Point A have population of 100, and point B have population of 150. I do find buffer of these 2 points and it is intersect. I ...
1
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0answers
76 views

Intersection between a ray from lat, lon, alt, with pan, tilt and earth's surface

I have a problem that consists of finding the intersection point between a ray from a given lat, lon, alt, that is looking to a given pan and tilt angles and the earth's surface. I need the lat, lon ...
3
votes
1answer
335 views

PostGIS intersection function

I have a problem with intersection function. I built my query following http://manual.linfiniti.com/en/postgis/geometry.html, 5.7 section. I made my clip object, a red linestring frame: But after ...
1
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0answers
46 views

How to get intersected points between polygon and line in desired order

I have polygon for example "POLYGON((5 1, 6 1, 6 5, 5 5, 5 1))" that I want to intersect with line "LINESTRING(0 2, 10 2, 10 3, 0 3, 0 4, 10 4)" and get intersection points in the order that they ...
1
vote
1answer
27 views

Software needed to cross-reference geocodes to a Shapefile

I do not have any GIS software except Microsoft MapPoint. I have State district KML and Shapefiles of the districts. I am assuming these are for ArcGIS. I do not want to draw maps. Instead, ...
1
vote
0answers
51 views

Trouble intersecting a polyline and contours (Hack index / stream length gradient index)

Working on creating polylines for measurement using SL index (hack index). So far I have the main trunk of a stream, and contours at 10m. What I am trying to do is a) get the elevation at each ...
0
votes
1answer
35 views

Cleaning up Line Features

I'm in the process of creating some routes for which I need left and right sections. I have an original streets feature class, which I used "copy parallels" on, and came up with something like the ...
1
vote
0answers
113 views

How to best intersect vector data with raster data?

I have Open Street Map [OSM] data imported so that I can access the geometry of buildings. I have also loaded SRTM digital height data from NASA from a GeoTIFF raster. I have projected the raster into ...
1
vote
1answer
47 views

Two boundary sets intersect - some are genuine diffferences, others slivers resulting from poor digitising. How to differentiate?

Problem: I have two boundary sets. Intersecting reveals that there are genuine differences between them - as expected. However, there are also a host of slivers due to their being digitised by ...
3
votes
1answer
97 views

Find intercept WGS84 coordinates between two segments defined by (Lat1-Long1 and Lat2-Long2) and (Lat3-Long3 and Lat4-Long4)

I need to determine the WGS84 coordinates for a point that is defined by the interception of two segments represented by two sets of WGS84 coordinates each (lat1-long1, lat2-long2) and (lat3-long3, ...
4
votes
2answers
159 views

How to optimize a ST_Within query to count lightning occurrences inside a country?

I just started learning PostGIS, and right now i'm trying to count the number of lightning strikes in my country (Brazil in this case). I have the following tables: earth_feed --> This holds the ...
0
votes
0answers
58 views

Arcobjects/Arcgis Engine — geoprocessing within a buffer?

I have a point layer and a polyline layer (each contains more than 100k records), I would like to process the polyline layer within point buffer zones. For example, for each point in the point layer, ...
1
vote
1answer
102 views

ST_Intersects incorrectly returning false in PostGIS

I have a shapefile created from ArcMap that contains about 400 geometry's. I've added this shapefile into PostGIS using the shp2pgsql tool. I am trying to use the ST_Intersects function to determine ...
0
votes
1answer
68 views

How to find line segment between line intersections?

Given 1 non-self-intersecting line (red) and 2 other non-self-intersecting lines (light-green), what is the best way to find the coordinates of the line in between the 2 intersections? I threw this ...
1
vote
1answer
420 views

OGR Layer Intersection

I am using what I would describe as the most primitive method of doing intersection with OGR. The short script below describes how I do it. Is there a best way of doing this? from osgeo import ...
0
votes
0answers
81 views

Draw point on google map

i try to add google map on my own wms and wfs layer. everything works but when i create point, i intersect point geometry and my geojson data. So without googlemap it was run. But when add google map, ...
1
vote
1answer
53 views

How to preserve line segment ObjectIDs in point output from line Intersect?

I am using the Intersect tool in ArcGIS for Desktop 10.1 to identify all the intersections in a polyline shapefile. The tool generates a point shapefile, but when I inspect the data it does not ...
0
votes
2answers
105 views

Intersect and MBR in POSTGIS and Mysql

I would like to know if POSTGIS and MySql with Spatial Extension use true geometry to find intersections/overlaps between geospatial objects. But i don't find it precisely in the documentation. I know ...
7
votes
1answer
533 views

Find Nearest Line Segments to Point

Background From a known Point, I require to establish the nearest surrounding "visible perimeter" against a table of MultiLineStrings, as shown on the diagram. I've searched this site with a number ...
1
vote
1answer
94 views

creating a st_contains query with geographies not geometries

I'm trying to find all the geography points that are contained in a geography polygon, let say all the traffic lights within a given city or neighborhoods, how can i convert this working st_intersect ...
1
vote
1answer
87 views

determining what polygons intersect another layer

I am attempting to establish what spatial relationship exists (if any) between two layers. I have two layers - one is a road network with a buffer of 500m, and the other is a collection of polygons ...
1
vote
2answers
252 views

unionize intersections of merged polygons

[Updated quesion] I am using the following code to merged polygons from shapefiles for the purpose of calculating the surface area; library(maptools) library(rgdal) library(rgeos) #enter slots, ...
2
votes
1answer
202 views

Creating buffers that will not overlap in QGIS

I am dealing with a .shp with a number of points in it. The distances between points range from ~300m to 5km. I wish to create a 1 km buffer around each point with as little overlap as possible. Each ...
2
votes
3answers
207 views

Produce a list of polygons that a line crosses

I have a polyline feature class and a polygon feature class. What I want to do is add a field to the lines that lists all polygons that touch the line. This is effectively performing a ...
1
vote
1answer
60 views

Mismatch in area calculation using Field Calculator vs Group Stats in QGIS 2.0

I have two polygon files (A being my area of interest and B being a categorised land cover layer). Both layers were in the same projection (projected and not geographic). Using QGIS 2.0, I used the ...
1
vote
1answer
70 views

Separating distinct lines in PostGIS

I have a table of linestring segments in Postgis. These segments make up distinct non-intersecting lines as shown by the diagram. To add confusion the direction of the linestrings are not uniform. I ...
2
votes
2answers
112 views

How to check if vertex exists (on polyline) based on location of point layer using ArcPy?

Using ArcGIS for Desktop Advanced 10.1 (with all extensions) I am building a centerline network that will be used by a MapObjects program to do routing based on "turns at any vertex" (as opposed to ...
0
votes
1answer
207 views

Maximum size on the bounding box with ST_MakeEnvelope and && and geography column in PostGIS?

I've done quite a few google searches, but haven't managed to find anything that has helped me directly. I've got a few features in a PostGIS table with a geography column. The features are focused ...
3
votes
2answers
129 views

Is there a way to speed up gIntersections for large spatial objects?

I'm attempting to perform a gIntersection of a big grid on a shapefile for country boundaries, so that I can calculate the % area of each grid cell that lies within the country. It takes a few seconds ...
0
votes
0answers
21 views

Program crashes when trying to do intersection.

I'm trying to get the intersection between a highways shapefile and some states in Mexico but it seems that the program always crashes. I attach the images of what I'm trying to do and the error that ...
0
votes
1answer
142 views

Intersecting polygons in Oracle

Have a polygon in table 2 with its id, no and geometry. In table 1 I have polygons with the same fields. The polygon in table in intersects with a few polygons from table 1.What I am trying to do is ...
2
votes
1answer
121 views

Separate a polygon in different polygons depending of the distance to another polygon

I have a reference polygon "R", and others polygons (in grey). I want to separate each grey polygon in multiple polygons, depending on the distance to R with different Buffers : - The red line is R ...
2
votes
1answer
319 views

PostGIS: Calculate the length of just the portion of linestring that intersect with a polygon

I want to calculate the portion of the linestring that lies within the limits of a polygon. Better with an image What is the length of the portion of linestring within Province A? and within ...
4
votes
1answer
369 views

How to use the Intersects function in the Field Calculator of QGIS?

I would like to have an example on how to use the Intersects function in the Field Calculator of QGIS. Basically, I want to know which feature from a polylines layer intersects a polygons layer and ...
2
votes
2answers
684 views

Intersect (analysis) of polygons generating empty output

I have previously asked a question on determining the area of polygons with another polygon boundary. Determining the area of each polygon within a polygon boundary? I came to the conculsion that ...
1
vote
3answers
186 views

ST_Intersection point of two 3D linestrings - how is the Z value calculated?

I have two 3D linestrings (geometry type LINESTRING Z) in a PostGIS database that intersect in 2D space, but not in 3D space. Given that there is technically no 'shared portion' of geometry in 3D, how ...
1
vote
1answer
97 views

Load Raster Values into Shapefile [duplicate]

I have a shapefile containing many points. Some of these points fall within an area for which I have raster data. I would like to load the values of the raster which underlie each point into the ...
3
votes
2answers
157 views

geospatial libraries like postgis

I'm pretty comfortable with postgis, but I realized that for part of my application, having a database is pretty heavy. I'd like to be able to take a stream of Point objects and check against an in ...
5
votes
1answer
282 views

Performance in calculating raster statistics in PostGIS

I'm trying to calculate raster statistics (min, max, mean) for each polygon in a vector layer using PostgreSQL/PostGIS. This GIS.SE answer describes how to do this, by calculating the intersection ...
1
vote
1answer
148 views

How to calculate the intersect two shapefiles [duplicate]

I have two shapefiles. 1. the clinic buffers 500m area. 2. the postcode area. Is there a simple way to calculate the intersect two shapefiles ? I'm using QGIS Dufour. I tried to use fTools to ...
1
vote
1answer
87 views

How to perform intersect operations in the Field Calculator in QGIS?

How to use the Intersect function? How would I specify to REPLACE layer1.field1 with layer2.field2 WHEN layer1.geometry INTERSECTS layer2.geometry Is that feasible in QGIS?
2
votes
0answers
57 views

How to copy the contents of an attribute from one vector layer to another one that touches it or intersects it?

I have 2 layers that intersect, called layer A and layer B. Layer A has an attribute (X) that I want to copy wholesale (for the whole layer) to layer B, so that when object A1 intersects object B1, ...
3
votes
1answer
125 views

intersection between two multipolygons yielding anomalous GeometryCollection object full of LineString's & Polygon's (trying to get intersect area)

Normally when I call the #intersection method on a multipolygon to find the intersection shape on another multipolygon I get a multipolygon returned back to me. Either that or something else I can ...
0
votes
0answers
87 views

Line - Line and Line - Polygon intersection in WGS84

What is the correct way (which formula, what algorithm, etc) to determine the intersection point of two lines specified in Lat/Lon coordinates on a WGS84 model? Note that the lines might be very long ...
1
vote
1answer
214 views

Intersection of multi-polygons in postgis

How can I get the intersection of 3 multi-polygons in postgis? I have three geometry collection and I want a fourth with the result of intersection of the other three. ...