Thanks James,
I understand what you are saying and have read the relevant section in the
manual, but we did a test where we constructed an inclined regular grid of
heights at 45 deg to the horizontal to discount the influence of "flyers".
VM calculated the slope to be 70.71% (dip) where we would have expected it
to be 100% (hade). Your manual suggests that VM should have produced the
latter result (p306).
I have since been told that "the values are the complements of each other.
One is called the dip, the other the hade. it is an old geological
difference between mining engineers and geologists. Geologists calculate
dip (in the same manner that VM does). Miners calculate Hade (in the
manner that the WS group does)."
Our dilemma is that we perform slope analyses for the land development
industry which has to comply with strict guidelines when it comes to
developing steep sites. VM has been presenting an optimistic result for our
clients and could have legal ramifications for us down the track.
Would it be possible to have both solutions included in future releases of
VM. We are currently using a work-around by deliberately adjusting our
slope intervals to give a "corrected" result.
Regards
Peter Graham
WS Group - Mackay
Ph: +61 (07) 4951 2911
Fx: +61 (07) 4953 1319
Em: [EMAIL PROTECTED]
Web: www.wsgroup.com.au
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED]]On Behalf Of James Harvie
Sent: Wednesday, 1 December 1999 5:28 AM
To: Mapinfo L
Cc: [EMAIL PROTECTED]
Subject: RE: MI VM Slope Analysis
Peter,
In Vertical Mapper the slope for a grid node is calculated by averaging the
slopes of the eight triangle faces that are formed from the surrounding
nodes. The average is taken so that the resulting slope value is not overly
influenced by "flyers" in the dataset. I hope this helps.
James Harvie
Vertical Mapper Product Manager
Northwood Geosience Ltd.
43 Auriga Drive, K2E 7Y8
Nepean, Ontario, Canada
613-224-2020
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED]]On Behalf Of
[EMAIL PROTECTED]
Sent: Wednesday, November 24, 1999 9:37 PM
To: [EMAIL PROTECTED]
Subject: MI VM Slope Analysis
A question to all you Vertical Mapper experts.
When performing a slope analysis it would appear that VM calculates slope
(degrees or percent, it doesn't matter) by dividing vertical displacement by
slope distance.
Whereas, in Australia we calculate slope by dividing vertical displacement
by horizontal distance.
Is this normal or is VM incorrectly calculating slope?
Regards
Peter Graham
WS Group - Mackay
Ph: +61 (07) 4951 2911
Fx: +61 (07) 4953 1319
Em: [EMAIL PROTECTED]
Web: www.wsgroup.com.au
----------------------------------------------------------------------
To unsubscribe from this list, send e-mail to [EMAIL PROTECTED] and put
"unsubscribe MAPINFO-L" in the message body, or contact [EMAIL PROTECTED]
----------------------------------------------------------------------
To unsubscribe from this list, send e-mail to [EMAIL PROTECTED] and put
"unsubscribe MAPINFO-L" in the message body, or contact [EMAIL PROTECTED]
----------------------------------------------------------------------
To unsubscribe from this list, send e-mail to [EMAIL PROTECTED] and put
"unsubscribe MAPINFO-L" in the message body, or contact [EMAIL PROTECTED]
