Placing Lines Within Polygons Uniquely

 I'll be honest, there might be a function to do this but I couldn't find it and it was only going to take a few minutes so let's take a look.  I have a bunch of triangles for and  XML file that need to be subdivided into areas that are defined by polygons.  I need to make sure that the triangles are kept intact and that there are no duplicates.  In my case it didn't need to be an exact science and I wasn't worried about the edges.  My solution was to check each triangle against a polygon and if the first point of the triangle was within the polygon it would be flagged, or in this case the layer changed.  I just banged it out and I may make changes but for now it does the trick.

print ('line_change_line_in_polygon.py modified   06:25 2023/11/07')

# Change layer of line that starts within polygon.

'''

Author: Dennis Shimer dshimer@gmail.com

License: cc-by-sa  http://creativecommons.org/licenses/by-sa/3.0/

'''

Ws=PyVrWs()

Line=PyVrLine()

BoundingLine=PyVrLine()

Gui=PyVrGui()

CheckLayer=600

NewLayer=1001

PointsFound=0

WsNum=Ws.Aws()

PromBox = VrPromBox ('Check lines in Polygon.', 30, 1)

PromBox.AddInt ('Layer to check', CheckLayer, 1, 32000)

PromBox.AddInt ('Change layer to', NewLayer, 1, 32000)

if (PromBox.Display(0) == 0):

CheckLayer=PromBox.GetIntByPrompt('Layer to check')

NewLayer=PromBox.GetIntByPrompt('Change layer to')

BoundingLine.Id()

print (CheckLayer,BoundingLine.GetLayer())

Gui.ProgInit('Lines',Ws.GetLineCount(WsNum))

for EntNum in range ( Ws.GetLineCount(WsNum)):

Gui.ProgSet(EntNum)

if CheckLayer == Ws.GetLineLayer(WsNum,EntNum):

Line.Load (WsNum, EntNum)

X,Y,Z=Line.GetPoint(0)

if BoundingLine.IsPointInside (X,Y):

# print (X,Y,Z)

PointsFound=PointsFound+1

Line.SetLayer(NewLayer)

Line.ReRec(1)

# Line.Plot()

Gui.ProgReset()

print (PointsFound)

 

Modifying LiDAR Intensity in Vr Applications

I actually don't have the patience to look back through posts with regard to modifying LiDAR data so I'll just drop this one in as an example of how simple it can be.  This will have limited usefulness because it is fixing an apparent shortcoming in Vr that will no doubt be rectified at any moment, but hopefully the example will continue to be useful.  The current problem is that points created via dsmare (DSM Area) have a nice RGB value, but sometimes it would be nice to have Intensity as well. Rather than making it tricky I found that if I just add the R, G, and B values and divide by 3 it provides a useful "intensity like" display.    
There are only a couple lines that do anything productive so I'll just explain them.

print 'rgb2int.py modified 12:23 PM 9/25/2018'
# Set point intensity based on rgb
'''
License: cc-by-sa  http://creativecommons.org/licenses/by-sa/3.0/

'''
Ws=PyVrWs()
Punt=PyVrPunt()
Gui=PyVrGui()
WsNum=Ws.Aws()
PointBufferCount=Ws.GetPuntBufCount(WsNum)

Gui.ProgInit('Points',Ws.GetPuntBufCount(WsNum))
for PointBufferNumber in range(PointBufferCount):
    Punt.Load(WsNum,PointBufferNumber)
    Gui.ProgSet(PointBufferNumber)
    for PuntNum in range(Punt.GetCount()):
        x,y,z,PuntA,r,g,b= Punt.GetPuntRgb (PuntNum)
        PuntA['Int']=int((r+g+b)/3)
        Punt.ChgPuntA (PuntNum, PuntA)
    Punt.ReRec()
Gui.ProgReset()
PyVrGr().Replot()

 You need to have a PyVrPunt object to work with.  This object will be used to load up a "Point Buffer" full of LiDAR data which we can then step through the individual point data.  Note that you need to loop over the whole file loading each of the point buffers into the Punt object. This is done with the first for loop

for PointBufferNumber in range(PointBufferCount):

As we step through all the buffers, each one needs to be loaded and then it will be stepped through loading up the individual points hence the next for loop.

for PuntNum in range(Punt.GetCount()):

There are several ways to get particular data items from individual points and much of the data is stored in an attribute dictionary known as PuntA.  Many times I just load up PuntA, query it, make decisions, then make changes based on what I find.  In this case it is handy that the method that extracts the R,G,B data also pulls out PuntA at the same time because Intensity is stored within PuntA.  The first thing that needs doing is grabbing the data for the individual point.


x,y,z,PuntA,r,g,b= Punt.GetPuntRgb (PuntNum)

Then we just turn right around and push the intensity into the current PuntA dictionary and record the modified attributes back to the point.


PuntA['Int']=int((r+g+b)/3)
Punt.ChgPuntA (PuntNum, PuntA)

Once all the points are changed in the currently loaded buffer (Punt), the whole buffer can be re-recorded.


Punt.ReRec()

The Punt class is fully documented in the Python Programming section of the documentation but it basically comes down to knowing if you are creating or modifying something inside the attribute dictionary or outside it and working with the appropriate methods.

Musings on being a senior programmer

In some context's the title would mean being an experienced, admired, authoritative person.  Alas for me it just means being old, and in retrospect using the word programmer is a bit of a stretch.  Maybe it is harder to remember things because every day I have so much more important information to pack away for later retrieval, or maybe it is just harder to remember.  As we evolve as a company I find myself adding layer names and function keys that I know I'll use again but not often enough that I'll probably remember them.  Gone are the days when a function was one of 120 three digit numbers (which of course I still remember because I've been using most of them for 30 years). I quit trying to remember things I can Google long ago so why not treat the new layers and functions the same, after all if I expose myself to them often enough I'll eventually remember, and if I don't then searching is easy enough.  Enter sealay and seafk.  Now if I forget what the layer number is, but remember that it had the word "Wall" in the name I can just
sealay wall
and like magic I am presented with a list of options which when selected issues a lay= command.

  Likewise if I forget a function key and don't want the entire funkey command list I can just...
seafk odot
and all the appropriate function keys are presented.

It must be nice to have a limitless unhindered storage capacity, but for those of us who have more useful years in the past than in the future, search is our friend.

They both essentially work the same, just one searches the layer names and one searches the function keys.  Here is an example but you get the idea.

print 'seafky.py modified 9:11 AM 7/27/2017'# Display FKeys matching search string
'''
Copyright 2017 Dennis Shimer
Vr Mapping copyright Cardinal Systems, LLC
No warranties as to safety or usability expressed or implied.
Free to use, copy, modify, distribute with author credit.

Prompts user for Fkey name (or any part) then displays Fkey
'''

def lines2lists(AListOfDataLines):
    DataList=[]
    for Line in AListOfDataLines:
        DataList.append(Line.split())
    return DataList

PrintList=[]

if VrArgs:
    SearchText=VrArgs[0]
else:
    SearchText=PyVrGui().InputDialog ('Search String', 'Partial Funkey Name')[1]

FunKeyFile = open(VrCfg().GetFkeyFileName() , 'r')
FunkeyData = FunKeyFile.readlines()
FunKeyFile.close()
DataList = lines2lists(FunkeyData)

for DataLine in DataList :
    if len(DataLine) == 3 :
        if DataLine[1]=='KeyName':
            if DataLine[2].upper().count(SearchText.upper()):
                PrintList.append(DataLine[2])

if PrintList:
    PromBox = VrPromBox ("Run Fkey", 60, 1)
    PromBox.AddList ("Function Key", 40, len(PrintList)+1, 0)
    for FkeyItem in PrintList:
        PromBox.AddListItem (FkeyItem)
    if (PromBox.Display(0) == 0):
        RunFkey = PromBox.GetListByPrompt ("Function Key")
    else: RunFkey=0
    if RunFkey : PyVrGui().PushKeyin(RunFkey)
    else: PyVrGui().MsgBox('No Match to {:s}'.format(SearchText), 'Matching Layers')

Going from Zero to "How did I ever get along before that" in three minutes

The other day I heard about a little indicator app ( aka bookmarks-indicator ) for Ubuntu that sits nicely on the task bar and allows you to drill down through the disk hierarchy by simply mousing over the icon.  It displays the folder names as you move through the system, auto expanding as you pause over a file name, showing individual files in each folder and opening them when you click.  One minute I didn't even know I wanted this ability and three minutes later I wondered how I ever survived without it.  The fact that is was just a couple dozen easy to read lines of python was even funner.  

Jump ahead to this morning and I came across a bunch of lines that just needed to have one particular point removed from them.  Long story, but on this particular job it happens on a fairly regular basis.  Well I've always had a program to straighten a line, removing all points between to identified locations, but I just needed to delete one point, and doing it with a single click would just be that much easier.  Granted EditVertex set to delete is 95% of the way to what I want but honestly sometimes you just need to step outside for a break to grab that last 5% especially if you can do so with a few lines of code.  And let's be honest it's funner than working anyway.

Hence dellpt.py

print 'dellpt.py modified 9:06 AM 9/20/2016'
# Delete Line Point
'''
Copyright 2016 Dennis Shimer
Vr Mapping copyright Cardinal Systems, LLC
No warranties as to safety or usability expressed or implied.
Free to use, copy, modify, distribute with author credit.

Deletes a single point identified on a line.
'''

Ws=PyVrWs()
Line=PyVrLine()
while Line.Id() != -1:
    Ws.UndoBegin(WsNum,"dellpt")
    PntNum=Line.GetIdPoint ()
    Line.DelPoint (PntNum)
    Line.ReRec()
    Line.Plot()
    PyVrGr().Replot()
    Ws.UndoEnd(WsNum)

Simple tools for simple tasks (an appreciation for....)

Maybe because I am fairly simple minded, I have always had a deep appreciation for "The Unix Philosophy" which to my thinking involves the idea that if you just need to solve a simple little problem quickly you just throw together a simple little tool to do it but at the same time make sure that there is a way to chain these little tools together in a way that can make the aggregate a truly useful and maybe powerful solution. The integration of this idea into the programs I interact with minute by minute all day every day (and the fact that the first versions were on Unix) make Mike Kitaif one of my heroes.  Yes almost every function, option, toolset has an easy, GUI, comprehensive way of dealing with it but at the same time almost all have a simple command equivalent with arguments that can be built upon using function keys, macros, or incredibly the python interpreter. When you combine this with the fact that rather than a monolithic database for hanging on to all the settings they are usually stored in tiny easily accessible (sometimes even text) files you get the opportunity to make the system do almost anything you can dream.

A great example of all this came up recently when I realized that under certain conditions I wanted to under certain conditions be able to view a particular vertical slice of LiDAR data and set the coloring based on elevation sub-slices.  There is of course a way to do this using the GUI for the poidis command.

There are also fairly straightforward ways to set all these things from the command line.
http://www.vrmapping.net/help5/index.html?point_display.htm

However, what I really wanted was the ability to input a minimal amount of information (base elevation and total slice thickness) and then have it display exactly what I wanted with the colors set to the sub slices (thickness divided by total number of available slices, or 20 currently) and here is where the python comes in. Granted the programming is about at the level of an 8 year old with a Raspberry Pi but you get the idea.

print 'viewsl.py modified 6:06 AM 5/6/2016'
# Views a slice of lidar with color by slice elevation.
'''
Copyright 2016 Dennis Shimer
Vr Mapping copyright Cardinal Systems, LLC
No warranties as to safety or usability expressed or implied.
Free to use, copy, modify, distribute with author credit.

A little more user friendly option to the Vr alternative which uses an
external parameter file which can be referenced by other programs
like bumvsl

'''
import os
import man
Ws=PyVrWs()
WsNum=Ws.Aws()
Gui=PyVrGui()

MinZ = Ws.GetMinMax (WsNum)[2]
MaxZ = Ws.GetMinMax (WsNum)[5]
AverageZ = (MaxZ+MinZ)/2.0

#In case the parameter file was never created before or can't be read for some reason
BaseZ=AverageZ
DelZMin=MinZ-AverageZ
DelZMax=MaxZ-AverageZ
Thickness=MaxZ-MinZ

ParFileName=VrCfg().GetVrHomeDir()+'/hostdir/viewslice.par'
if not os.path.isfile(ParFileName):
     open(ParFileName,'w').write('{:.2f} {:.2f} {:.2f} {:.2f}'.format(BaseZ,DelZMin,DelZMax,Thickness))
elif not os.path.getsize(ParFileName):
     open(ParFileName,'w').write('{:.2f} {:.2f} {:.2f} {:.2f}'.format(BaseZ,DelZMin,DelZMax,Thickness))
Params=open(ParFileName,'r').read().split()
BaseZ=float(Params[0])
Thickness=float(Params[3])

#In case the user passes in the numbers from the command line.
if VrArgs:
      BaseZ=float(VrArgs[0])
      Thickness=float(VrArgs[1])

PromBox = VrPromBox ("Set Z Slice", 30, 1)
PromBox.SetFocus()
PromBox.AddDouble('BaseZ',BaseZ,2)
PromBox.AddDouble('Thickness',Thickness,2)

if not VrArgs:
      if PromBox.Display(1)==0:
          BaseZ=PromBox.GetDoubleByPrompt('BaseZ')
          Thickness=PromBox.GetDoubleByPrompt('Thickness')
open(ParFileName,'w').write('{:.2f} {:.2f} {:.2f} {:.2f}'.format(BaseZ,DelZMin,DelZMax,Thickness))

#Just use the numbers to pass along arguments to the built in commands.
print BaseZ,DelZMin,DelZMax,Thickness
Gui.PushKeyin ('PoiFilZsl  On')
Gui.PushKeyin ('PoiFilZsl  BasZ {:.2f}'.format(BaseZ))
Gui.PushKeyin ('PoiFilZsl  MinDel {:.2f}'.format(0))
Gui.PushKeyin ('PoiFilZsl  MaxDel {:.2f}'.format(Thickness))

NumberOfSlices=20
SliceThickness = Thickness*1.08/NumberOfSlices #1.08 because it minimizes the top white slice.
print MinZ,MaxZ,SliceThickness,NumberOfSlices
Gui.PushKeyin ('PoiColSli  On')
Gui.PushKeyin ('PoiColSli  ResZ')
Gui.PushKeyin ('PoiColSli SliZ {:d} {:.2f} {:.2f}'.format(1,0,BaseZ))
CurrentElevation=BaseZ
for CurrentSliceNumber in range(2,NumberOfSlices):
    Gui.PushKeyin ('PoiColSli SliZ {:d} {:.2f} {:.2f}'.format(CurrentSliceNumber,CurrentElevation,CurrentElevation+SliceThickness))
    CurrentElevation+=SliceThickness
Gui.PushKeyin ('PoiColSli SliZ {:d} {:.2f} {:.2f}'.format(NumberOfSlices,CurrentElevation,1000000))

PyVrGr().Replot()

*Read the Wikipedia article if for no other reason than to better appreciate some of the men who helped make this all possible.