VrOne/Python Programming

ON-LINE REFERENCE DOCUMENTATION

CARDINAL SYSTEMS, LLC

386-439-2525

www.cardinalsystems.net mike@cardinalsystems.net

PyVrDtm Class Reference

VrOne/Python DTM routines More...

Members

PyVrDtm (UseVrDtm,CgNum)
Reset ()
ResetMinMax (MinX, MinY, MinZ, MaxX, MaxY, MaxZ)
AddPoint (x, y, z)
SetAreaToModel (AreaToModel)
SetVerbose (Verbose)
SetWsToConsid (WsToConsid)
Process ()
ProcessWs ()
GetElev (x, y)
SetFreeFlag (FreeFlag)
IsDtmValid ()
SetPointsLayer (Layer)
SetBreaksLayer (Layer)
GetMinZ ()
GetMaxZ ()
GetBoundary ()
IsPointInside (x, y)
GetContour (Elev)
GetFirstContour ()
GetNextContour ()
GetFirstTriangle ()
GetNextTriangle ()
FindTriangles (x, y)
FindTrianglesFromEdge (ex1, ey1, ex2, ey2)
GetTriangle (TriNum)
GetTriangleInfo (TriNum)

Detailed Description

The PythonVrOne DTM Class contains routines for creating and working with DTM models. This includes DTM processing, contour generation, and elevation querying.

IMPORTANT USAGE NOTE: There are two main ways to use the DTM class.

The first is by getting a reference to the main VrOne DTM object. This is done by creating a PyVrDtm object with a parameter of True, and an optional surface number. This method allows you to share the DTM data with the current VrOne session. Any DTM’s created with this method will be active in VrOne for things such as cursor tracking.
The second is by creating a new DTM object that is separate from the VrOne DTM object. This is done by creating a PyVrDtm object with a parameter of False. This allows you to create a DTM that is completely separate from the active DTM in VrOne. VrOne has no knowledge of DTM’s created using this method, and cursor tracking will not follow a DTM created with this method.

See the dtmtest.py and testslope.py scripts for sample code that use the PyVrDtm class.

Member Function Documentation

PyVrDtm (UseVrDtm, CgNum)

Returns a DTM object. This object is either a newly created DTM object or a reference to the VrOne DTM object, depending on what value is passed in for UseVrDtm.

UseVrDtm	True = Return reference to existing VrOne DTM object. False = Return new DTM object.
CgNum	Optional. Surface number to use. 0-7, or –1 to use active surface.
returns	(Object)
	Object	PyVrDtm oject.

Reset ()

Reset DTM parameters so a new Process command can be called. Always call this command or ResetMinMax before calling Process. This method does not need to be called if using the ProcessWs method.

ResetMinMax (MinX, MinY, MinZ, MaxX, MaxY, MaxZ)

Reset DTM parameters so points can be manually added to the DTM. This should always be called before points are added using AddPoint. All points added using AddPoint must fall within these bounds. If you are not adding points manually with AddPoint, then you can use Reset instead.

MinX	Min x of bounding box covering extents of points to be added to DTM
MinY	Min y of bounding box covering extents of points to be added to DTM
MinZ	Min z of bounding box covering extents of points to be added to DTM
MaxX	Max x of bounding box covering extents of points to be added to DTM
MaxY	Max y of bounding box covering extents of points to be added to DTM
MaxZ	Max z of bounding box covering extents of points to be added to DTM

AddPoint (x, y, z)

Manually adds a point to the DTM model. ResetMinMax() must be called before adding the first point. The Process method must be used after manually adding points, or the points will be ignored.

x	X coordinate of point to add.
y	Y coordinate of point to add.
z	Z coordinate of point to add.

SetAreaToModel (AreaToModel)

Sets workspace area to model.

AreaToModel

0=Entire workspace, 1=Window area only

SetVerbose (Verbose)

Sets verbose mode.

Verbose

0=Verbose mode off, 1=Verbose mode on

SetWsToConsid (WsToConsid)

Sets workspace to consider.

WsToConsid

0=All Workspaces, 1= Current Workspace

Process ()

Processes the DTM TIN only. Does not place triangles or contours into the current VrOne file. This will process points and breaklines according to the current DTM parameters. If you would like to only process manually added points, then call SetPointsLayer and SetBreaksLayer with empty strings before beginning processing.

ProcessWs ()

Processes the complete DTM. Ignores any manually added points, and places triangles, contours, boundary line, and depressions into the current VrOne file according to the current DTM parameters. This command is equivalent to using the RUNDTM command in VrOne.

GetElev (x, y)

Returns elevation of point within the DTM.

x	Floating point X coordinate of point where elevation should be computed.
y	Floating point Y coordinate of point where elevation should be computed.
returns	(z)
	z	Return elevation.

SetFreeFlag (FreeFlag)

Determines whether DTM will remain in memory after processing. This must be True for cursor tracking. This value may default to True or False depending on the currently loaded DTM parameters.

FreeFlag

True = Keep DTM in memory. False = Remove DTM from memory.

IsDtmValid ()

Returns status of DTM.

returns	(ret)
	ret	True = DTM is valid, False = DTM is not valid.

SetPointsLayer (Layer)

Sets layer for DTM Points.

Layer

String value representing layers to use when searching for DTM points. This may be a number line (Ex. '1-6 25 65')

SetBreaksLayer (Layer)

Sets layer for DTM Breaks.

Layer

String value representing layers to use when searching for DTM breaklines. This may be a number line (Ex. '1-6 25 65')

GetMinZ ()

Returns minimum Z value of DTM.

returns	(ret)
	ret	Floating point value of minimum Z coordinate in DTM.

GetMaxZ ()

Returns maximum Z value of DTM.

returns	(ret)
	ret	Floating point value of maximum Z coordinate in DTM.

GetBoundary ()

Returns points along DTM boundary.

returns	(ret)
	ret	List of tuples containing points that make up DTM boundary. Each tuple contains x,y,z floating point coordinate.

Example

Bndry = Cg.GetBoundary()

for coord in Bndry:

x, y, z = coord

IsPointInside (x, y)

Returns status of point in relation to DTM boundary.

x	X coordinate of point to check
y	Y coordinate of point to check
returns	(ret)
	ret	True = Points is inside DTM boundary, False = Points is outside DTM boundary

GetContour (Elev)

Returns points for all contours at a given elevation.

Elev	Elevation of contour to return.
returns	(ret)
	ret	List of tuples containing points that make up all contours at this elevation. Each tuple contains code,x,y,z where x,y,z are floating point coordinate of the point location, and code is an integer number that is 0 when a new contour should be started.

Example

def SaveContour(Contour, Layer):

Line = PyVrLine ()

Line.SetLayer (Layer)

# Go through contour points

for coord in Contour:

code, x, y, z = coord

# New contour starting if code is 0

if (code == 0 and Line.GetNumXyz() > 0):

Line.Rec (Ws.Aws())

Line.Reset()

Line.AddPoint (x, y, z)

# Make sure last contour is saved

if (Line.GetNumXyz() > 0):

Line.Rec (Ws.Aws())

Line.Reset()

ContElev = 125.0

Contour = Cg.GetContour (ContElev)

if (len(Contour) > 1):

SaveContour (Contour, 2)

GetFirstContour ()

Used with GetNextContour to walk through all contours at a specified interval.

returns	(Stat, Elev, Contours)
	Stat	0=More contours to follow, -1=No more contours available
	Elev	Elevation of current Contour
	Contours	list of tuples containing points that make up all contours at this elevation. Each tuple contains code,x,y,z where x,y,z are floating point coordinate of the point location, and code is an integer number that is 0 when a new contour should be started.

Example

Stat, Elev, Contour = Cg.GetFirstContour (2) # Get contours with 2’ interval

SaveContour (Contour, int(Elev))

while (Stat == 0):

Stat, Elev, Contour = Cg.GetNextContour ()

SaveContour (Contour, int(Elev))

GetNextContour ()

Used with GetFirstContour to walk through all contours at a specified interval.

returns	(Stat, Elev, Contours)
	Stat	0=More contours to follow, -1=No more contours available
	Elev	Elevation of current Contour
	Contours	list of tuples containing points that make up all contours at this elevation. Each tuple contains code,x,y,z where x,y,z are floating point coordinate of the point location, and code is an integer number that is 0 when a new contour should be started.

Example

# Walk through all triangles

(Tri, x1, y1, z1, x2, y2, z2, x3, y3, z3) = Dtm.GetFirstTriangle ()

while (Tri):

(Tri, x1, y1, z1, x2, y2, z2, x3, y3, z3) = Dtm.GetNextTriangle ()

GetFirstTriangle ()

Used with GetNextTriangle to walk through all triangles.

returns	(TriNum, x1, y1, z1, x2, y2, z2, x3, y3, z3)
	TriNum	Triangle number. If 0, then no triangle was found.
	x1	X Coordinate location of triangle vertex 1
	y1	Y Coordinate location of triangle vertex 1
	z1	Z Coordinate location of triangle vertex 1
	x2	X Coordinate location of triangle vertex 2
	y2	Y Coordinate location of triangle vertex 2
	z2	Z Coordinate location of triangle vertex 2
	x3	X Coordinate location of triangle vertex 3
	y3	Y Coordinate location of triangle vertex 3
	z3	Z Coordinate location of triangle vertex 3

GetNextTriangle ()

Used with GetFirstTriangle to walk through all triangles.

returns	(TriNum, x1, y1, z1, x2, y2, z2, x3, y3, z3)
	TriNum	Triangle number. If 0, then no triangle was found.
	x1	X Coordinate location of triangle vertex 1
	y1	Y Coordinate location of triangle vertex 1
	z1	Z Coordinate location of triangle vertex 1
	x2	X Coordinate location of triangle vertex 2
	y2	Y Coordinate location of triangle vertex 2
	z2	Z Coordinate location of triangle vertex 2
	x3	X Coordinate location of triangle vertex 3
	y3	Y Coordinate location of triangle vertex 3
	z3	Z Coordinate location of triangle vertex 3

FindTriangles (x, y)

Find triangles that share point x,y. If x,y is inside a triangle then only 1 triangle will be returned. If x,y is on edge, then 1 (if boundary triangle) or 2 triangles will be returnred. If x,y is on vertex, then multiple triangles may be returned.

x	X coordinate of search point
y	Y coordinate of search point
returns	(Triangles)
	Triangles	List of triangles found

Example

(Triangles) = Dtm.FindTriangles (x, y)

print "Found %d triangles." % len(Triangles)

for Triangle in Triangles:

(Slope, Aspect, Cx, Cy) = Dtm.GetTriangleInfo (Triangle)

FindTrianglesFromEdge (ex1, ey1, ex2, ey2)

Find triangles that share the edge between ex1, ey1 and ex2, ey2. Will return 1 triangle if edge is on boundary, or 2 triangles if edge is inside tin.

ex1	X coordinate of point 1
ey1	Y coordinate of point 1
ex2	X coordinate of point 2
ey2	Y coordinate of point 2
returns	(Triangles)
	Triangles	List of triangles found

Example

(Triangles) = Dtm.FindTrianglesFromEdge (x1, y1, x2, y2)

print "Found %d triangles." % len(Triangles)

for Triangle in Triangles:

(Slope, Aspect, Cx, Cy) = Dtm.GetTriangleInfo (Triangle)

GetTriangle (TriNum)

Get vertex coordinates for a single triangle.

TriNum	Triangle number.
returns	(x1, y1, z1, x2, y2, z2, x3, y3, z3)
	x1	Vertex 1 x coordinate
	y1	Vertex 1 y coordinate
	z1	Vertex 1 y coordinate
	x2	Vertex 2 x coordinate
	y2	Vertex 2 y coordinate
	z2	Vertex 2 y coordinate
	x3	Vertex 3 x coordinate
	y3	Vertex 3 y coordinate
	z3	Vertex 3 y coordinate

GetTriangleInfo (TriNum)

Get additional triangle information.

TriNum	Triangle number.
returns	(Slope, Aspect, cx, cy)
	Slope	Slope of triangle 0.0 to 1.0
	Aspect	Direction of slope in radians with 0.0=north
	cx	Barycenter x coordinate
	cy	Barycenter y coordinate