Greetings -
I am processing some geotechnical data that is geolocated on a CAD drawing (Bentley dgn is the original pedigree).
This has been exported as a dxf file and brought into GRASS with v.in.dxf – no problem.
The region is set up in state plane coordinates (KY-N) with US survey feet as units.
When I run v.report on the layer that contains the boring data the file content is displayed, for example:
37|G_PF_SYMB3_PR|text|5B-303|1212081.497014|279650.475464|0
38|G_PF_SYMB3_PR|text|5B-305|1211936.354207|279753.605789|0
39|G_PF_SYMB3_PR|text|5B-306|1211736.052427|279843.95891|0
Using 5B-305 as an example, when I display the points and query using v.what, it produces:
East: 1212909.91005291
North: 279431.95238095
Map: borings
Mapset: PERMANENT
Type: Point
Line: 58
Point height: 0.000000
Layer: 3
Category: 38
Driver: dbf
Database: /Users/stu/grassdata/Kennedy_SPC/PERMANENT/dbf/
Table: borings_g_pf_symb3_pr
Key column: cat
cat : 38
layer : G_PF_SYMB3_PR
entity : text
These coordinates bear little resemblance to the v.report values.
Opening the dxf file in an editor and poking about, I found what appears to be the data set for 5B-305 (it is the only time 5B-305 appears in the file):
AcDbEntity
8
G_PF_SYMB3_PR
100
AcDbText
10
1212909.151125 **
20
279430.832539 **
30
0.0
40
12.0
1
5B-305 **
50
7.581985
7
1 1 Plan
100
These correspond fairly well to the values produced by v.what.
The question for anyone patient enough to still be with me is – what is v.report reporting? There appears to be no pattern to the dx and dy between the two reports over a reasonable sampling of the borings.
Partial answer! I was about to hit the send button, but decided first to run a search in the dxf file for the coordinates that are shown in v.report. To my surprise there was one hit:
AcDbEntity
8
G_PF_SYMB3_PR
100
AcDbText
10
1211936.354207 **
20
279753.605789 **
30
0.0
40
12.0
1
5B-329 **
50
7.581985
7
1 1 Plan
100
The coordinates for 5B-305 in v.report are actually those of 5B-329! So the data appear to be shuffled rather than distorted.
Thanks for any help you can provide ~
Stu