topic Re: Can I label a points layer perpendicular to a line layer? in Gas and Pipeline Questions

Can I label a points layer perpendicular to a line layer?

PaulWirth — Mon, 30 Apr 2018 12:08:19 GMT

I have a points layer (Electrical Transmission structures) and a Transmission line layer. The points layer sits on top of the line layer and because the line layer changes direction all the time it is hard to label the points layer sometimes. What I would like to do is label the points layer perpendicular to the line layer.

Does anyone have an answer for me?

Re: Can I label a points layer perpendicular to a line layer?

XanderBakker — Sun, 12 Dec 2021 00:55:16 GMT

It would be important to know what software you are using (and the version). Are you using desktop (Pro or ArcMap) or ArcGIS Online?

In case of Desktop, you could create a script to generate a field with the rotation based on the bisector. A few years ago I created a tool to define service areas of transmission tower applying the rotation based on the bisector (the green polygons in the image below):

The rotation determined by the tool could be written to the transmission towers and those can be used to define the rotation of the label. See the code below. The angles are determined on lines 51, 73 and 93.

import arcpy

def main():
    import os
    arcpy.env.overwriteOutput = True

    # input fc
    fc = arcpy.GetParameterAsText(0)  # r'C:\...\data.gdb\Torres'
    fld_label = arcpy.GetParameterAsText(1)  # 'LABEL'
    fld_orden = arcpy.GetParameterAsText(2)  # 'orden'
    buf = arcpy.GetParameter(3)  # 20m servidumbre
    fc_out = arcpy.GetParameterAsText(4)  # poligonos de servidumbre

    # spatial reference
    sr = arcpy.Describe(fc).spatialReference

    # dicts, listado para orden
    arcpy.AddMessage('Generar dictionarios con coordenadas, labels y orden...')
    flds = (fld_orden, 'SHAPE@')
    dct_crds = {r[0]: r[1] for r in arcpy.da.SearchCursor(fc, flds)}
    flds = (fld_orden, fld_label)
    dct_lbl = {r[0]: r[1] for r in arcpy.da.SearchCursor(fc, flds)}

    # create list of points and order list
    arcpy.AddMessage('Ordenar torres...')
    lst_ptgs = [pntg for orden, pntg in sorted(dct_crds.items())]
    lst_orden = sorted(dct_crds.keys())

    # create output featureclass
    arcpy.AddMessage('Crear featureclass de salida...')
    ws, fc_name = os.path.split(fc_out)
    arcpy.CreateFeatureclass_management(ws, fc_name, "POLYGON", None, None, None, sr)

    # add fields
    arcpy.AddField_management(fc_out, fld_label, "TEXT", None, None, 50)
    flds_out = ('SHAPE@', fld_label)

    # empty lists for output features
    lst_puntos = []
    lst_lineas = []
    lst_poligonos = []

    # start insert cursor
    arcpy.AddMessage('Recorrer torres...')
    with arcpy.da.InsertCursor(fc_out, flds_out) as curs:

        # first polygon
        if len(lst_ptgs) >= 2:
            pntg_1 = lst_ptgs[0]
            pntg_2 = lst_ptgs[1]
            angle_12 = getAngle(pntg_1, pntg_2)
            cut_line = createPerpendicularCutLine(pntg_1, angle_12, buf, sr)

            # create polygon
            polygon = createServidumbre(pntg_1, cut_line, buf, sr)

            # generate and insert output row
            lbl1 = dct_lbl[lst_orden[0]]
            arcpy.AddMessage(' - procesar: {0}'.format(lbl1))
            curs.insertRow((polygon, lbl1, ))


        # intermediate polygons
        for i in range(1, len(lst_ptgs) - 1):
            # read points
            pntg_a = lst_ptgs[i - 1]
            pntg_1 = lst_ptgs[i]
            pntg_2 = lst_ptgs[i + 1]

            # get angles and bearings
            angle_1a = getAngle(pntg_1, pntg_a)
            angle_12 = getAngle(pntg_1, pntg_2)
            bearing_l = (angle_1a + angle_12) / 2.0

            # create cut lines
            cut_line = createCutLine(pntg_1, bearing_l, buf, sr)

            # cut polygon
            polygon = createServidumbre(pntg_1, cut_line, buf, sr)

            # generate and insert output row
            lbl1 = dct_lbl[lst_orden[i]]
            arcpy.AddMessage(' - procesar: {0}'.format(lbl1))
            curs.insertRow((polygon, lbl1, ))


        # last polygon
        if len(lst_ptgs) >= 2:
            pntg_1 = lst_ptgs[len(lst_ptgs) - 2]
            pntg_2 = lst_ptgs[len(lst_ptgs) - 1]

            # get angles and bearings
            angle_21 = getAngle(pntg_2, pntg_1)
            cut_line = createPerpendicularCutLine(pntg_2, angle_21, buf, sr)

            # cut polygon
            polygon = createServidumbre(pntg_2, cut_line, buf, sr)

            # generate and insert output row
            lbl1 = dct_lbl[lst_orden[len(lst_ptgs) - 2]]
            arcpy.AddMessage(' - procesar: {0}'.format(lbl1))
            curs.insertRow((polygon, lbl1, ))

    arcpy.AddMessage('Listo...')


def createServidumbre(pntg, cut_line, servidumbre, sr):
    '''
    Create rectangle using the cutline
    and the size of the servidumbre
    '''

    angle_cut_line = getAngleLine(cut_line)
    tmp_pntg1 = pntg.pointFromAngleAndDistance(angle_cut_line, servidumbre / 2.0, 'PLANAR')
    tmp_pntg2 = pntg.pointFromAngleAndDistance(angle_cut_line + 180, servidumbre / 2.0, 'PLANAR')

    # create corner points
    pntg1a = tmp_pntg1.pointFromAngleAndDistance(angle_cut_line - 90, servidumbre / 2.0, 'PLANAR')
    pntg1b = tmp_pntg1.pointFromAngleAndDistance(angle_cut_line + 90, servidumbre / 2.0, 'PLANAR')
    pntg2a = tmp_pntg2.pointFromAngleAndDistance(angle_cut_line + 90, servidumbre / 2.0, 'PLANAR')
    pntg2b = tmp_pntg2.pointFromAngleAndDistance(angle_cut_line - 90, servidumbre / 2.0, 'PLANAR')

    polygon = arcpy.Polygon(arcpy.Array([pntg1a.firstPoint, pntg1b.firstPoint,
        pntg2a.firstPoint, pntg2b.firstPoint, pntg1a.firstPoint]), sr)

    return polygon


def getAngleLine(line):
    pntg1 = arcpy.PointGeometry(line.firstPoint, line.spatialReference)
    pntg2 = arcpy.PointGeometry(line.lastPoint, line.spatialReference)
    return getAngle(pntg1, pntg2)


def createPerpendicularCutLine(pntg, angle, dist, sr):
    pntg_cut_1 = pntg.pointFromAngleAndDistance(angle - 90, dist * 2.0, 'PLANAR')
    pntg_cut_2 = pntg.pointFromAngleAndDistance(angle + 90, dist * 2.0, 'PLANAR')
    cut_line = arcpy.Polyline(arcpy.Array([pntg_cut_1.firstPoint, pntg_cut_2.firstPoint]), sr)
    return cut_line


def createCutLine(pntg, bearing1, buf, sr):
    bearing2 = bearing1 + 180
    pntg_cut_1 = pntg.pointFromAngleAndDistance(bearing1, buf * 10.0, 'PLANAR')
    pntg_cut_2 = pntg.pointFromAngleAndDistance(bearing2, buf * 10.0, 'PLANAR')
    cut_line = arcpy.Polyline(arcpy.Array([pntg_cut_1.firstPoint, pntg_cut_2.firstPoint]), sr)
    return cut_line


def createLine(pntg1, pntg2, sr):
    return arcpy.Polyline(arcpy.Array([pntg1.firstPoint, pntg2.firstPoint]), sr)


def getAngle(pntg1, pntg2):
    return pntg1.angleAndDistanceTo(pntg2, method='PLANAR')[0]


if __name__ == '__main__':
    main()‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

Re: Can I label a points layer perpendicular to a line layer?

PaulWirth — Mon, 30 Apr 2018 13:52:02 GMT

Desktop 10.5.1 or ArcGIS Pro 2.1.1

I am not a big time programmer.

Re: Can I label a points layer perpendicular to a line layer?

XanderBakker — Mon, 30 Apr 2018 13:59:38 GMT

Is it possible for you to share a sample of the data? I could have a look if I can adjust the script to what you need. The result would be an additional field with the rotation in the point layer.

Re: Can I label a points layer perpendicular to a line layer?

PaulWirth — Mon, 30 Apr 2018 14:12:15 GMT

I have to look into it, but it might be possible. Which layer do you want? Points or Lines.

Re: Can I label a points layer perpendicular to a line layer?

XanderBakker — Mon, 30 Apr 2018 14:20:16 GMT

It could (or should) be both. Or if the points follow the order (sequence) of the line one could determine the angles of the lines based on only the points. Otherwise, one has to determine the angles of both line parts based on the line. It also matter is the line is a single line, or each segment from tower to tower is a feature. Would be could to see the data to understand those aspects, since it determines how the code should be changed.

Re: Can I label a points layer perpendicular to a line layer?

GIS_Rookie — Tue, 15 Feb 2022 10:17:55 GMT

Hi, @XanderBakker !

Could I get a help with this script?

I have the same queastion as @Paul 😕

Re: Can I label a points layer perpendicular to a line layer?

XanderBakker — Tue, 15 Feb 2022 23:19:26 GMT

Hi @GIS_Rookie ,

Then I suppose I have to reply with a question similar to the one I asked Paul. Do you have a sample of data that you can share? That will help understand what you have and what you are looking for.

Re: Can I label a points layer perpendicular to a line layer?

XanderBakker — Wed, 16 Feb 2022 17:47:48 GMT

Hi @GIS_Rookie ,

Thanks for sharing the sample of data. There are a couple of ways you can proceed. I created a line featureclass using the cut lines and changed it a bit to have it align to the left and I included the pole information for labeling. Have a look at the result below:

See below the Python code I used (in the Python window of ArcGIS Pro):

def getAngleLine(line): pntg1 = arcpy.PointGeometry(line.firstPoint, line.spatialReference) pntg2 = arcpy.PointGeometry(line.lastPoint, line.spatialReference) return getAngle(pntg1, pntg2) def createPerpendicularCutLine(pntg, angle, dist, sr): pntg_cut_1 = pntg.pointFromAngleAndDistance(angle - 90, dist * 2.0, 'PLANAR') pntg_cut_2 = pntg.pointFromAngleAndDistance(angle + 90, dist * 2.0, 'PLANAR') cut_line = arcpy.Polyline(arcpy.Array([pntg_cut_1.firstPoint, pntg_cut_2.firstPoint]), sr) return cut_line def createCutLine(pntg, bearing1, buf, sr): bearing2 = bearing1 + 180 pntg_cut_1 = pntg.pointFromAngleAndDistance(bearing1, buf * 1.5, 'PLANAR') pntg_cut_2 = pntg.pointFromAngleAndDistance(bearing2, buf * 0, 'PLANAR') cut_line = arcpy.Polyline(arcpy.Array([pntg_cut_1.firstPoint, pntg_cut_2.firstPoint]), sr) return cut_line def createLine(pntg1, pntg2, sr): return arcpy.Polyline(arcpy.Array([pntg1.firstPoint, pntg2.firstPoint]), sr) def getAngle(pntg1, pntg2): return pntg1.angleAndDistanceTo(pntg2, method='PLANAR')[0] import os arcpy.env.overwriteOutput = True # input fc fc = r'D:\GeoNet\TransmissionLabel\point.shp' fld_label = 'Pole' fld_orden = 'Pole' buf = 20 fc_out = r'D:\GeoNet\TransmissionLabel\cutline02.shp' # spatial reference sr = arcpy.Describe(fc).spatialReference # dicts, listado para orden flds = (fld_orden, 'SHAPE@') dct_crds = {r[0]: r[1] for r in arcpy.da.SearchCursor(fc, flds)} flds = (fld_orden, fld_label) dct_lbl = {r[0]: r[1] for r in arcpy.da.SearchCursor(fc, flds)} # create list of points and order list lst_ptgs = [pntg for orden, pntg in sorted(dct_crds.items())] lst_orden = sorted(dct_crds.keys()) # create output featureclass ws, fc_name = os.path.split(fc_out) arcpy.CreateFeatureclass_management(ws, fc_name, "POLYLINE", None, None, None, sr) # add fields arcpy.AddField_management(fc_out, fld_label, "TEXT", None, None, 50) flds_out = ('SHAPE@', fld_label) # empty lists for output features lst_puntos = [] lst_lineas = [] lst_polylines = [] # start insert cursor with arcpy.da.InsertCursor(fc_out, flds_out) as curs: # first polygon if len(lst_ptgs) >= 2: pntg_1 = lst_ptgs[0] pntg_2 = lst_ptgs[1] angle_12 = getAngle(pntg_1, pntg_2) cut_line = createPerpendicularCutLine(pntg_1, angle_12, buf, sr) # generate and insert output row lbl1 = dct_lbl[lst_orden[0]] arcpy.AddMessage(' - procesar: {0}'.format(lbl1)) curs.insertRow((cut_line, lbl1, )) # intermediate polygons for i in range(1, len(lst_ptgs) - 1): # read points pntg_a = lst_ptgs[i - 1] pntg_1 = lst_ptgs[i] pntg_2 = lst_ptgs[i + 1] # get angles and bearings angle_1a = getAngle(pntg_1, pntg_a) angle_12 = getAngle(pntg_1, pntg_2) bearing_l = (angle_1a + angle_12) / 2.0 # create cut lines cut_line = createCutLine(pntg_1, bearing_l, buf, sr) # generate and insert output row lbl1 = dct_lbl[lst_orden[i]] arcpy.AddMessage(' - procesar: {0}'.format(lbl1)) curs.insertRow((cut_line, lbl1, )) # last polygon if len(lst_ptgs) >= 2: pntg_1 = lst_ptgs[len(lst_ptgs) - 2] pntg_2 = lst_ptgs[len(lst_ptgs) - 1] # get angles and bearings angle_21 = getAngle(pntg_2, pntg_1) cut_line = createPerpendicularCutLine(pntg_2, angle_21, buf, sr) # generate and insert output row lbl1 = dct_lbl[lst_orden[len(lst_ptgs) - 2]] arcpy.AddMessage(' - procesar: {0}'.format(lbl1)) curs.insertRow((cut_line, lbl1, ))

The other way would be to write the angle to the points. This can be achieved like this:

def getAngle(pntg1, pntg2): return pntg1.angleAndDistanceTo(pntg2, method='PLANAR')[0] import os arcpy.env.overwriteOutput = True # input fc fc = r'D:\GeoNet\TransmissionLabel\point.shp' fld_label = 'Pole' fld_orden = 'Pole' fld_angle = 'ANGLE2' buf = 20 # spatial reference sr = arcpy.Describe(fc).spatialReference # dicts, listado para orden flds = (fld_orden, 'SHAPE@') dct_crds = {r[0]: r[1] for r in arcpy.da.SearchCursor(fc, flds)} flds = (fld_orden, fld_label) dct_lbl = {r[0]: r[1] for r in arcpy.da.SearchCursor(fc, flds)} # create list of points and order list lst_ptgs = [pntg for orden, pntg in sorted(dct_crds.items())] lst_orden = sorted(dct_crds.keys()) dct_res = {} # first polygon if len(lst_ptgs) >= 2: pntg_1 = lst_ptgs[0] pntg_2 = lst_ptgs[1] angle_12 = getAngle(pntg_1, pntg_2) + 90.0 # generate and insert output row lbl1 = dct_lbl[lst_orden[0]] dct_res[lbl1] = angle_12 # intermediate polygons for i in range(1, len(lst_ptgs) - 1): # read points pntg_a = lst_ptgs[i - 1] pntg_1 = lst_ptgs[i] pntg_2 = lst_ptgs[i + 1] # get angles and bearings angle_1a = getAngle(pntg_1, pntg_a) angle_12 = getAngle(pntg_1, pntg_2) bearing_l = (angle_1a + angle_12) / 2.0 # generate and insert output row lbl1 = dct_lbl[lst_orden[i]] dct_res[lbl1] = bearing_l # last polygon if len(lst_ptgs) >= 2: pntg_1 = lst_ptgs[len(lst_ptgs) - 2] pntg_2 = lst_ptgs[len(lst_ptgs) - 1] # get angles and bearings angle_21 = getAngle(pntg_2, pntg_1) - 90.0 # generate and insert output row lbl1 = dct_lbl[lst_orden[len(lst_ptgs) - 2]] dct_res[lbl1] = angle_21 # start insert cursor flds_out = (fld_label, fld_angle) with arcpy.da.UpdateCursor(fc, flds_out) as curs: for row in curs: lbl = row[0] if lbl in dct_res: angle = dct_res[lbl] else: pass # angle = 400 curs.updateRow((lbl, angle, ))

Re: Can I label a points layer perpendicular to a line layer?

GIS_Rookie — Thu, 17 Feb 2022 12:46:45 GMT

Oh, thank you for quick response 🙂

Second script worked well for me, but I have one queastion about ANGLE2. Is there a way to get positive angle not negative? Example in picture, marked with red.

Re: Can I label a points layer perpendicular to a line layer?

XanderBakker — Thu, 17 Feb 2022 14:22:15 GMT

Hi @GIS_Rookie ,

I suppose you can do something like this at the end of the script:

# start insert cursor flds_out = (fld_label, fld_angle) with arcpy.da.UpdateCursor(fc, flds_out) as curs: for row in curs: lbl = row[0] if lbl in dct_res: angle = dct_res[lbl] if angle < 0: angle += 360 else: pass # angle = 400 curs.updateRow((lbl, angle, ))

Re: Can I label a points layer perpendicular to a line layer?

GIS_Rookie — Thu, 17 Feb 2022 14:49:37 GMT

Thanks @XanderBakker ! This worked for me 🙂

Just curious about why those numbers are heading to north and south, not in one direction? And some of numbers lost their directions. Maybe there is some kind of explanation? Tried to build 1 script from 2 but without success.

P.S. Saw your other posts (Translating the lowest overhead power lines into a continuous surface). They are also interesting!

Re: Can I label a points layer perpendicular to a line layer?

XanderBakker — Thu, 17 Feb 2022 23:41:06 GMT

Hi @GIS_Rookie ,

So, ArcGIS has its labeling engine Maplex that has a lot of settings you can play with to get the result you want. I understand that it would be better to have them all point in a certain direction in this case. However, if you have a line that describes a circular movement, it would be best that in a certain location the text switches its orientation in order to be closer to horizontal and enable readability for the end-user.

I also had some issues with the texts near the start or end of the line, not sure what is going on there.

Re: Can I label a points layer perpendicular to a line layer?

MarcoConopio1 — Mon, 18 Apr 2022 02:27:06 GMT

Hi @XanderBakker !

I am trying to run your script and I have some questions.

What is the fc_out shapfile? Is this the line shapefile to which the labels will be perpendicular to?
I tried running both of the script, with the assumption that the fc_out is the alignment to which the labels will be perpendicular to, and I keep getting this error

Thank you and would greatly appreciate any help!

Re: Can I label a points layer perpendicular to a line layer?

XanderBakker — Tue, 19 Apr 2022 12:41:39 GMT

Hi @MarcoConopio1 ,

The error is pointing to the use of a field that does not exist in the featureclass. Can you check that the fields with names assigned to the variables "fld_orden" and "fld_label" exist in your featureclass?

Re: Can I label a points layer perpendicular to a line layer?

OzzOutao_UoM — Tue, 11 Apr 2023 18:29:04 GMT

Hi, @XanderBakker . Thanks a lot for your script, it’s very useful.

I am having an issue with angles as when my ‘ANGLE2’ field gets populated the only value I get is: -116.907208734888 (for every row).
I am basically trying to draw a short line that will mark 1 km along the road. I have created points along the road, and now trying to label them with ‘___’.
I want this labels to be perpendicular to the road.
I have added two fields to my points shapefile (‘Pole’ with values as ‘___’ (data type: text), and “ANGLE2” with empty values (data type: double)).

Please take a look at the attached file for a visual explanation.

I will appreciate any advise, thanks!