North Points South & Fixed Points Move
Wonder if anyone can tell me what is going on here? I have a set of files that produce a grid, fixed points and a surface image as per the attached (fairly boring I'm sorry - image removed to keep the file size down) The output strangely has the north arrow pointing south (I am using 5.2.6 - however older datasets seem to process OK so far). The fixed points and the surface image are aligned almost perfectly, but the grid appears to be about 10m too far north relative to the fixed points and surface image. Perhaps my grid definition is somehow using a different co-ordinate system or the fixed points are been moved (in error?) by some loop closure routine? The displacement seems to be the same regardless of the std deviations following the point definitions. There are no survey legs, only fixed points. The grid is set by; grid-size 500 100 100 metres # coordinate grid The fixed points are set by; #btmleft centreline #Set Co-ordinate System and Entrances #------------------------------------ cs EPSG:27200 #NZ Map Grid 1949 #Recorded Entrance co-ordinates fix btmleft 2483000 8038000 000 0 0 0 #NZMG #Identified Survey Stations #-------------------------- station btmleft "btm left cnr of map" endcentreline #topright centreline #Set Co-ordinate System and Entrances #------------------------------------ cs EPSG:27200 #NZ Map Grid 1949 #Recorded Entrance co-ordinates fix topright 2486000 8042000 000 0 0 0 #NZMG #Identified Survey Stations #-------------------------- station topright "top right cnr of map" endcentreline The surface image is set by; surface cs EPSG:27200 #NZ Map Grid 1949 bitmap "./Parapara South GIS Plan geo98 contour 10000 A2.jpg" \ [349 344 2483000 8038000 2050 2602 2486000 8042000] endsurface
This is strange - it looks like you are using some strange coordinate system. Are you able to isolate this problem to some simple data-set? It looks, there are just few fixed points and config file. Regards, S. On Tue, Feb 10, 2009 at 8:01 AM, Bruce Mutton <bruce.mutton@paradise.net.nz> wrote:
Wonder if anyone can tell me what is going on here?
I have a set of files that produce a grid, fixed points and a surface image as per the attached (fairly boring I'm sorry - image removed to keep the file size down)
The output strangely has the north arrow pointing south (I am using 5.2.6 – however older datasets seem to process OK so far).
The fixed points and the surface image are aligned almost perfectly, but the grid appears to be about 10m too far north relative to the fixed points and surface image.
Perhaps my grid definition is somehow using a different co-ordinate system or the fixed points are been moved (in error?) by some loop closure routine? The displacement seems to be the same regardless of the std deviations following the point definitions. There are no survey legs, only fixed points.
The grid is set by;
grid-size 500 100 100 metres # coordinate grid
The fixed points are set by;
#btmleft
centreline
#Set Co-ordinate System and Entrances
#------------------------------------
cs EPSG:27200 #NZ Map Grid 1949
#Recorded Entrance co-ordinates
fix btmleft 2483000 8038000 000 0 0 0 #NZMG
#Identified Survey Stations
#--------------------------
station btmleft "btm left cnr of map"
endcentreline
#topright
centreline
#Set Co-ordinate System and Entrances
#------------------------------------
cs EPSG:27200 #NZ Map Grid 1949
#Recorded Entrance co-ordinates
fix topright 2486000 8042000 000 0 0 0 #NZMG
#Identified Survey Stations
#--------------------------
station topright "top right cnr of map"
endcentreline
The surface image is set by;
surface
cs EPSG:27200 #NZ Map Grid 1949
bitmap "./Parapara South GIS Plan geo98 contour 10000 A2.jpg" \
[349 344 2483000 8038000 2050 2602 2486000 8042000]
endsurface
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This is strange - it looks like you are using some strange coordinate system. Are you able to isolate this problem to some simple data-set? It looks, there are just few fixed points and config file.
Regards, S.
Stacho The data set is quite simple, more or less just code I sent you, patched together in what is becoming my standard dataset structure. There are only three fixed points and the surface image. I can send it to your personal mail if you want - with or without the image file (about 2MB). The co-ordinate system is the one I always use with Therion (with a few exceptions) - and is the standard one used by outdoor people in New Zealand. It has never given any problem until now, and my other data sets are fine (however I would not notice points plotted slightly incorrectly, as they all involve loop closures) Correction; I have one dataset with fixed points plotted on grid co-ordinates (for the purposes of labelling the co-ordinates) but these use an arbitrary magnetic north co-ordinate system. They plot perfectly on the grid to the full zoom available in the pdf file. The region covered by the problem map is known for it's para-normal phenomena, so perhaps that might explain it? Bruce
.
The output strangely has the north arrow pointing south (I am using 5.2.6 - however older datasets seem to process OK so >far).
The fixed points and the surface image are aligned almost perfectly, but the grid appears to be about 10m too far north >relative to the fixed points and surface image.
.
Problem solved. I discovered that I had entered co-ordinates 2000km too far north, so outside the valid range for this co-ord system. My scruffy topo map had 6's that looked like 8's. I guess when the log file says "meridian convergence (deg): 175.85" You know there's got to be a positioning problem, as it seems to hover around +-few degrees usually. So I'll concede Therion is working perfectly and user error is to blame! Apologies Bruce
On 17.2.2009, at 8:09, Bruce Mutton wrote:
I discovered that I had entered co-ordinates 2000km too far north, so outside the valid range for this co-ord system.
:) I just forgot a zero in coordinates and the map was to big for metapost even in scale 1:1000000 :) m.
participants (3)
-
Bruce Mutton -
Martin Sluka -
Stacho Mudrak