topic Re: rotate split polylines python arcpy in Python Questions

rotate split polylines python arcpy

AdebayoIshola — Mon, 24 Feb 2020 20:36:53 GMT

I have converted polygon edges into polylines which I have also split at vertices. I am trying to rotate the polygon edges (segments) at angles which I have stored in a field in an attribute table.

The angles I have are for the polygon vertices. How do I proceed with rotating the segments -- preferably by scripting?

For instance, in the above image with a polygon, I need to move those 2 line segments until the angle between them are at right-angle and repeat same for all vertex/corners of the polygon.

EDIT: Providing additional context

Re: rotate split polylines python arcpy

BlakeTerhune — Mon, 24 Feb 2020 22:24:46 GMT

Dan Patterson Has an interesting solution here. You can also check out this solution for rotating polygons as it should be the same. Here's another discussion That might be helpful. In short, there doesn't appear to be a single tool that will rotate a vector feature. Another discussion proposed converting the feature to a raster and using the Rotate tool, then converting back to a vector shape but I you'd lose precision along the way.

Re: rotate split polylines python arcpy

AdebayoIshola — Mon, 24 Feb 2020 22:29:25 GMT

Thank you, Blake. I am going through each now.

Re: rotate split polylines python arcpy

BruceHarold — Mon, 24 Feb 2020 22:34:39 GMT

I can't quite picture what you're looking to do but making squared off boundaries and rotating features is in this sample:

https://pm.maps.arcgis.com/home/item.html?id=9398bd2232cb4c8490b0b05015364d28

Re: rotate split polylines python arcpy

AdebayoIshola — Mon, 24 Feb 2020 22:53:38 GMT

Thank you, Bruce, for the link. But not sure that gets me to my goal.

Let me attempt to say it differently. So, the screenshot in the OP is a building footprint and the angles at the vertex aren't 90 degrees but should be -- digitizing error. I am now trying to adjust each corner which has angles such as 89.88 degrees to become 90 degrees. I am honestly not sure how to go about it and so I am in search of a solution.

Re: rotate split polylines python arcpy

BruceHarold — Mon, 24 Feb 2020 22:56:19 GMT

OK!

Regularize Building Footprint—Help | Documentation

Requires 3D Analyst extension.

Re: rotate split polylines python arcpy

AdebayoIshola — Mon, 24 Feb 2020 23:04:20 GMT

Thank you for this, Bruce. I am indeed aware of this tool but the current requirement is to script such a solution.

Re: rotate split polylines python arcpy

DanPatterson_Retired — Mon, 24 Feb 2020 23:48:50 GMT

Moving isn't the method. You have to pick the long side that will remain stationary, determine the short edge lengths and decide which you will use and derive its length. From the end points of the fixed long side and the desired edge length, you need to calculate the perpendicular offset points and replace the 'bad' long side points with these new values. You will then have a rectangle. You could do this iteratively, but that would be a wasted effort.

If these were constructed, make sure that the construct polygons with right angles is used.... 90 degrees all the time

Re: rotate split polylines python arcpy

AdebayoIshola — Sun, 12 Dec 2021 02:49:45 GMT

Absolutely spot on, Dan. This was my first thought line and I could get the lengths of the polygon sides using:

arcpy.MinimumBoundingGeometry_management(inFC, outFC,
                                            geometry_type="RECTANGLE_BY_AREA", 
                                            group_option="NONE", 
                                            mbg_fields_option=True)‍‍‍‍‍‍‍‍‍‍‍‍

The length and even orientation were computed after executing the above with split polylines (edges of the polygon) as the input Feature class. From there I wasn't sure what else I should be doing. Do you select the side with the longest line and then draw the perpendicular offsets at a static value or from the width values? I'm really not sure how to go about this.

PS: The screenshot in the OP is one sample.

Re: rotate split polylines python arcpy

DanPatterson_Retired — Sun, 12 Dec 2021 02:49:47 GMT

Your friend einsum.... The lengths are in sequential clockwise order from the start point (you can always determine/produce polygon points either as a separate feature class or values in a table.)

def lengths(poly):
    """Polyline lengths or polygon perimeter."""
    def _cal(a):
        """Perform the calculation, mini-e_leng."""
        diff = a[:-1] - a[1:]
        return np.sqrt(np.einsum('ij,ij->i', diff, diff))
    return _cal(poly)
    

[lengths(p) for p in [b1, b2, b3, b4]]

[array([ 10.0,  10.0,  10.0,  10.0]),
 array([ 10.0,  11.2,  11.2]),
 array([ 11.2,  10.0,  11.2]),
 array([ 11.2,  11.2,  10.0])]

# ---- If you want to experiment
 b1
array([[ 10.0,  0.0],
       [ 10.0,  10.0],
       [ 20.0,  10.0],
       [ 20.0,  0.0],
       [ 10.0,  0.0]])

b2
array([[ 20.0,  0.0],
       [ 20.0,  10.0],
       [ 30.0,  5.0],
       [ 20.0,  0.0]])

b3
array([[ 15.0,  20.0],
       [ 20.0,  10.0],
       [ 10.0,  10.0],
       [ 15.0,  20.0]])

b4
array([[ 10.0,  0.0],
       [ 0.0,  5.0],
       [ 10.0,  10.0],
       [ 10.0,  0.0]])
‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

Re: rotate split polylines python arcpy

AdebayoIshola — Wed, 26 Feb 2020 01:04:56 GMT

Hi Dan,

Thank you for your previous help and the tips you have provided but I need further help. Below is what I have:

A function that returns the maximum length of each of the rectangular polygons as a list. To be used as a reference edge/segment.
A function that returns the minimum length of each of the rectangular polygons as a list. To be used to construct length of a perpendicular edge.
A function that gets the coordinates of the endpoints of a polyline.

What would be an ideal approach to calculate the perpendicular offset points? Would I need to export/copy the longest edge of the polygon to a new FeatureClass before proceeding?

Any leads on a possible workflow would be very helpful.