# crossing.psp: Crossing Points of Two Line Segment Patterns In spatstat.geom: Geometrical Functionality of the 'spatstat' Family

## Description

Finds any crossing points between two line segment patterns.

## Usage

 `1` ``` crossing.psp(A,B,fatal=TRUE,details=FALSE) ```

## Arguments

 `A,B` Line segment patterns (objects of class `"psp"`). `details` Logical value indicating whether to return additional information. See below. `fatal` Logical value indicating what to do if the windows of `A` and `B` do not overlap. See Details.

## Details

This function finds any crossing points between the line segment patterns `A` and `B`.

A crossing point occurs whenever one of the line segments in `A` intersects one of the line segments in `B`, at a nonzero angle of intersection.

The result is a point pattern consisting of all the intersection points.

If `details=TRUE`, additional information is computed, specifying where each intersection point came from. The resulting point pattern has a data frame of marks, with columns named `iA, jB, tA, tB`. The marks `iA` and `jB` are the indices of the line segments in `A` and `B`, respectively, which produced each intersection point. The marks `tA` and `tB` are numbers between 0 and 1 specifying the position of the intersection point along the original segments.

If the windows `Window(A)` and `Window(B)` do not overlap, then an error will be reported if `fatal=TRUE`, while if `fatal=FALSE` an error will not occur and the result will be `NULL`.

## Value

Point pattern (object of class `"ppp"`).

\adrian

and \rolf

## See Also

`selfcrossing.psp`, `psp.object`, `ppp.object`.

## Examples

 ```1 2 3 4 5 6 7``` ``` a <- psp(runif(10), runif(10), runif(10), runif(10), window=owin()) b <- psp(runif(10), runif(10), runif(10), runif(10), window=owin()) plot(a, col="green", main="crossing.psp") plot(b, add=TRUE, col="blue") P <- crossing.psp(a,b) plot(P, add=TRUE, col="red") as.data.frame(crossing.psp(a,b,details=TRUE)) ```

spatstat.geom documentation built on April 15, 2021, 9:06 a.m.