I was intrigued by this problem and thought you'd be interested to know I was able to precisely locate your point along the 3d line using some simple Python scripting... 3D Analyst would have been useful particularly if the line contained curves; it did not (shapefiles do not support true curve geometry), so I was able to proceed with a very straightforward technique:- Use the distance formula (sqrt of the total sum of squares of the delta X,Y, and Z components) to cumulatively add segment distances between vertices until exceeding your target 3D distance on the line. Exiting at that point identifies the target segment 'range'.- Since dealing with a straight line segment (and the segment has been found in preceding step), the distance along the segment can be interpolated, i.e., it is the same proportion for each X, Y, Z component.- Once the point coordinates was calculated, I created a new point object using the calculated XYZ values and loaded it into your point layer via an insertcursor, which I then proceeded to use in 'breaking' the line at your 10170' distance (for verification).That last step I used so that the Calculate Geometry result for the 3d distance would be shown, see the attached.Again, note that if you had a fc with true curves, this interpolation method would not directly apply. I realize too this is not the Python forum, but thought this particular problem was very well suited for this approach. I 'cleaned' the below edited code from an IDLE session I was using, but didn't do a final test, so use at your discretion. I wrote this in a bit of a hurry to move on to something else, so just let me know if something doesn't make sense or I made an omission.No error trapping was used - for demo purposes only.Enjoy,Wayne
import arcpy, time
# Define a function to 'handle' 2 input point XYZ coords, computing the distance between.
def Dist3d(x1,y1,z1,x2,y2,z2):
deltaX = x1 - x2
deltaY = y1 - y2
deltaZ = z1-z2
distance = (deltaX**2 + deltaY**2 + deltaZ**2)**0.5
return distance
# Your shapefile (change the pathname accordingly).
shp = r'F:\Well_Bore\Well_Bore.shp'
# The point distance of interest, in this case, 10170.0
ptDistOfInterest = 10170.0
# Open a cursor, fetching the 1st row feature geometry.
rows = arcpy.SearchCursor(shp)
row = rows.next()
feat = row.Shape
# Listing a few properties, just curious...
# For the line feat in this thread:
print feat.type # prints 'polyline'
print feat.isMultipart # prints 'False'
print feat.partCount # prints '1'
print feat.length # prints '7034.13303256'
print feat.length3D # prints '16108.56262561997'
pointBgn = feat.firstPoint
print pointBgn.Z # prints '0.0'
pointEnd = feat.lastPoint
print pointEnd.Z # prints '-9381.4961999999941'
# The 'getPart' method returns an array of points.
theGeomPtArray = feat.getPart(0)
print theGeomPtArray.count # prints '197'
# Initializing a cumulative distance variable.
cumulativeD = 0.0
# Looping on the array, computing the distances, breaking at 10170.0...
for i in range(theGeomPtArray.count - 1):
pt1 = theGeomPtArray.getObject(i)
pt2 = theGeomPtArray.getObject(i + 1)
x1,x2 = pt1.X, pt2.X
y1,y2 = pt1.Y, pt2.Y
z1,z2 = pt1.Z, pt2.Z
cumulativeD += Dist3d(x1, y1, z1, x2, y2, z2)
if cumulativeD > ptDistOfInterest:
k = i
break
# Need to know the break point:
print k # prints '124'
# Need to know the current cumulative distance:
print cumulativeD # prints '10193.8322556'
# Need to fetch the 2 point objects from the array.
# The point distance specified is on this segment.
ptBrk = theGeomPtArray.getObject(k)
print ptBrk.X, ptBrk.Y, ptBrk.Z
# (2059018.4176586419, 254935.63821481168, -9491.9726999999984)
ptBrkNext = theGeomPtArray.getObject(k+1)
print ptBrkNext.X, ptBrkNext.Y, ptBrkNext.Z
# (2059003.0216920525, 254967.06695772707, -9491.7893999999942)
# Assign to vars to pass to the dist function...
x1,y1,z1 = ptBrkNext.X, ptBrkNext.Y, ptBrkNext.Z
x2,y2,z2 = ptBrk.X, ptBrk.Y, ptBrk.Z
segDistance = Dist3d(x1, y1, z1, x2, y2, z2)
print segDistance # prints '34.9976465974'
# The break in the loop exit value for cumulativeD included the segment.
# ...so the current segment has to be 'backed off' (subtracted).
priorDist = cumulativeD - segDistance
print priorDist # prints '10158.834609'
# Then, the distance to add from prior point:
addDist = 10170.0 - priorDist
print addDist # prints '11.1653910146'
# And with that, we compute the proportion for interpolation...
proportion = addDist/segDistance
print proportion # prints '0.319032623624'
# Proceed with the interpolation - X, Y, and Z:
Xonseg = proportion*(x1 - x2) + x2
Yonseg = proportion*(y1 - y2) + y2
Zonseg = proportion*(z1 - z2) + z2
# This is your point of interest, the coordinates:
print Xonseg # prints '2059013.5058430277'
print Yonseg # prints '254945.66500912118'
print Zonseg # prints '-9491.91422132'
# Pause in order to read the output.
time.sleep(10)
The output simply prints point coordinates to the screen, but say you wanted to see the point- for example, appended to the 'feature vertices to points' output shapefile (I did this as well), then that's easy using this (careful with schema-locking):
# Additional code, append the result to WellPointZM,
# for visual inspection purposes of the above code.
WellPointZM = r'F:\Well_Bore\WellPointZM.shp'
# First create a pt obj, using coordinates.
# This uses coords computed in previous code above...
pnt = arcpy.Point(Xonseg, Yonseg, Zonseg)
insertPt = arcpy.InsertCursor(WellPointZM)
addPT = insertPt.newRow()
addPT.Shape = pnt
insertPt.insertRow(addPT)
del insertPt # the cursor to 'unlock'
