Jackey,
I have seen this problem before and I think it is related to the fact
that you might have coincident points in your line. For example if the
first and second point in the linestring have the same value. This
causes problems when we try to compute the heading for that segment. If
you want me to check on that for you then send me a zip of the shapefile
with just the bad line in it.
If this is the case, we should probably write a bug ticket for this case.
-Steve
On 11/10/2011 8:03 PM, Jackey Cheung wrote:
Thanks for your comment, Havard Tveite.
As you suspected, the strange position (and also redundant) of arrows
is problem in figure 1. Since there is only one line there, we expect
only one set of (around 2~3) arrows were rendered. We can't figure out
why there are redundant arrows rendered at strange positions. The
expected outcome is only 2~3 arrows shall be rendered right around the
center of the line.
On Thu, Nov 10, 2011 at 4:49 PM, Havard Tveite<havard.tve...@umb.no> wrote:
Dear Jackey Cheung,
I am not sure what exactly you are trying to achieve.
Your arrows seem to point in the direction of the lines.
The topmost arrow in figure 1 is placed at a strange
position - is that the problem?
Some comments:
The result shown in image 2 is expected. The arrow
symbols are in this case placed at the start points of
the lines according to the centre point of the symbol's
bounding rectangle (except 0,0 is always taken as the
upper left corner of the bounding rectangle).
When using a negative GAP, the direction of the symbol
is the direction of the line at the (end)point.
In version 6.2, ANCHORPOINT is introduced to make it
possible to specify a different anchor point for the
symbol (http://mapserver.org/trunk/mapfile/symbol.html).
The centre point of the bounding box of your arrow_right
symbol will be at (17.5,7) in the symbol's coordinate
system, so the arrows will be placed somewhat shifted to
the right (in the direction of the arrow).
In 6.0, if you want the ends of the arrows to be aligned
with the start of the lines (when using geomtransform
start), you could use the following symbol:
SYMBOL
NAME "arrow_right_shift"
TYPE VECTOR
POINTS
30 6
52 6
50 0
60 7 # why 7.5?
50 14
52 8
30 8
30 6
END
FILLED TRUE
END
In 6.2, you will be able to specify this using
ANCHORPOINT 1 0.5
Håvard
On 11/10/2011 06:35 AM, Jackey Cheung wrote:
Hi all,
We are trying to render line direction on 6.0.1. However, there are
something weird with it.
SYMBOL
NAME "arrow_right"
TYPE VECTOR
POINTS
5 6
27 6
25 0
35 7.5
25 14
27 8
5 8
5 6
END
FILLED TRUE
END
LAYER
NAME "traffic_direction"
STATUS DEFAULT
TYPE LINE
MAXSCALEDENOM 5000
CONNECTIONTYPE POSTGIS
PROCESSING "CLOSE_CONNECTION=DEFER"
CONNECTION "host=xxxxxxx dbname=******* user=xxxxxxxxxx
password=************"
DATA "geom FROM view_render_traffic_direction USING
UNIQUE oid USING SRID=4326"
CLASS
NAME "Traffic Direction"
STYLE
ANGLE AUTO
SYMBOL "arrow_right"
SIZE 6
COLOR 0 0 250
GAP -200
#GEOMTRANSFORM "start"
END
END
END
The layer above is rendered as 1.PNG. We've checked that there are
only one line (ring) there, but arrows are rendered problematic.
Then we've tried to change GEOMTRANSFORM to "start" or "end", then
rings seem OK, but all arrows at intersections got crossed, as 2.PNG.
We've also tried to use OFFSET and GAP with positive and negative
combinations, but none can solve the problem.
Can anyone shed some light for us? Thanks in advance.
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