Where features overlap

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3
votes
1answer
1k views

Intersect two polylines using ArcObjects

I have two polylines and would like to find the intersection(s) using ArcObjects / VB.NET. I'm using the following code: Dim topoOp As ITopologicalOperator = TryCast(pTestPoly2, ...
4
votes
1answer
377 views

automating forest cover calculations with Python

I have a layer of forest cover comprising ~ 30,000 individual forest patches, and I need to calculate the amount of forest cover within a 5 km buffer of each patch. The buffers all overlap each other, ...
5
votes
2answers
2k views

Need help calculating forest cover within a buffer when it overlaps with other buffers

I'm new to ArcGIS and having real trouble getting this done… Hopefully someone can help. Thanks in advance! I have a layer showing forest cover in a landscape. I'm trying to create a 5km buffer ...
3
votes
2answers
706 views

How do I find the points of intersection between a small circle and a great circle?

I only actually need to intersect a great circle arc i.e. the shortest path between two points, with a given small circle. I found this tutorial for intersecting two great circle arcs, but ...
5
votes
1answer
252 views

Intermediate points on a small circle

I need to interpolate lat/lon points along a small circle, with a given centre and radius. I've successfully used these formulas for great circles. What is the equivalent for small circles?
3
votes
1answer
438 views

ITopologicalOperator.Intersect, how does this work?

I'm trying to intersect all features of a layer with another's but I'm getting the web ADF application stuck while executing the "ConstructUnion" function Here's the code I've written so far // ...
13
votes
6answers
7k views

How to use ST_Intersection?

Here's a quick summary about what I'm trying to do: I have 3 tables in Postgres, 'a' and 'b', each have a Polygon column, and 'c' has a Point column. What I'm trying to do here is to get the ...
3
votes
3answers
199 views

Is the Intersection Operation Commutative?

In map overlay, is intersection of map layers a commutative operation ie layer_A intersection layer_B = layer_B intersection layer_A? If layer A is a square and layer B is a triangle. In this case, (A ...
6
votes
1answer
837 views

Intersection of multiple layers in PostGIS

I need to write PL/pgSQL stored procedure for calculation of intersection of multiple layers. For example, for three layers A, B, C this function should return ABC geometry: Function takes as input ...
5
votes
1answer
342 views

Intersect between Surface and Ray

I am interested in finding the intersection of a Ray and a Surface in ArcObjects. I already know of two solutions. First solution is to use the Locate method of ISurface: Dim intersectionPoint As ...
3
votes
2answers
3k views

Measure the area of a polygon resulting from the intersection of two other polygons?

How can I measure the area of a polygon resulting from the intersection of two other polygons? If I use the measure tool or open the attribute table for the resulting polygon, it shows me the areas of ...
5
votes
1answer
1k views

How do I find the intersections of 2 circles on earths surface?

I have the circles' center in lat & long, as well as the radius in meters. How do I find the circles intersections? Edit: EXAMPLE: Circle 1: Center on Earth's surface (43.564627,-116.220524) ...
5
votes
1answer
2k views

How to get the intersecting polygon of two polygons? (using JSTS intersection)

I want to intersect two polygons within an OpenLayers layer. I found the JSTS library, which should be able to intersect two polygons, and return the new created polygon of the intersection. The ...
8
votes
4answers
2k views

Best way to find the polygons crossed by a line

I'm trying to find all the polygons crossed by a single line (a GPS track). I'm using the OGR library (from python) for computing this, but it's currently a bit 'brute-force' (and slow). For every ...
16
votes
4answers
3k views

PostGIS: Select features that do NOT intersect

This seems to me like such a simple question (and it probably is) yet I cannot seem to find an example that gives me the answer. Using PostGIS, I just want to select points that fall outside of ...
2
votes
1answer
718 views

Search Intersections with ArcGIS Server 10 without using Address Locator

Is there a way to search for intersections on a centerline layer in ArcGIS Server 10 without using an Address Locator? I can send direct queries to the centerline layer for individual road segments. ...
7
votes
7answers
2k views

Intersection algorithm that correctly handles the 180° meridian and poles?

Is there a well known intersection algorithm that correctly handles 180 meridian and poles? For example, let's say we have a list of latitude and longitude values that represent Antarctica. Let's ...
18
votes
4answers
6k views

Separate polygons based on intersection using PostGIS

I have a PostGIS table of polygons where some intersect with one another. This is what I'm trying to do: For a given polygon selected by id, give me all of the polygons that intersect. Basically, ...