[Manifold-l] Contouring; Contours from a DEM (surface)

[Colin Driscoll]

Ian
 
1. From the raw points data, Copy Paste As Surface (either table or
drawing). Set the parameters to suit and select an interpolation method.
Quickest would be flat triangulation. Surface Tools have more options.
Assuming the xy coords are geographic say MGA metres then all you need to do
is Assign the projection to the resulting surface (DEM).
 
2. You would have a DEM supplied- or created from 1. Open the DEM and use
Surface Contours and make your selections. Most likely would have to Assign
Projection to the supplied DEM.
 
HTH
 
Colin Driscoll
 
 


  _____  

From: manifold-l-bounces at directionsmedia.net
[mailto:manifold-l-bounces at directionsmedia.net] On Behalf Of scisoft
Sent: Tuesday, 4 December 2007 7:08 PM
To: manifold-l at lists.directionsmag.com
Subject: [Manifold-l] Contouring; Contours from a DEM (surface)



I have 2 questions about Manifold 8 that someone may be able to answer
simply - 

1.	Given X-Y-Z coordinates (let's say they're already in a Manifold
table, and the projection etc has been established), what is the simple
procedure to produce a contour of the Z values? Let us also assume that the
X-Y values are spaced in an almost-typical geological fashion, such as
points on the X axis at 25m centres and the lines 400m apart (ie, a 25m x
400m grid, oriented true NS-EW; a typical situation would have the "grid"
oriented at some angle to the true / geographic N-S, but we will ignore
that). The Z values might be height, or a soil component (eg, ppm Zn). 

2.	If a DEM (surface) model is already available of a similar X-Y-Z
dataset, and is geolocated (projection etc) and the data for the DEM
(surface) is only available in (say) ESRI ASCII grid format, what is the
simplest method to obtain a contour of the Z values from the DEM? (ie,
assume the raw X-Y-Z values as in 1. are not available). 

I'll probably have to follow up on any answers, to clarify how these simple
tasks would be achieved with Manifold. Alternative products achieve these
tasks in a very clear, well-defined way. 

  _____  

IL Thomas
GeoSciSoft  - Perth, Australia

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