How to create tiles accurately with MapServer?

[Teemu Mäkelä]

Hi,

Here is some more information:
- I use WMS connection to generate the tiles.
- There is no data projecting.
- Extents are determined in WMS request. Extents for each tile are 
calculated so that tiles do not overlap.

Manfred Meier sent the reply, which included some images representing the 
same problem.

Here is a sample of the image (pixels does not match because this example 
if just screen shot manually merged).


Here is a sample from the map file:
MAP
        NAME    AOI_map
        STATUS ON

        IMAGETYPE       png
        EXTENT  3425034.79743042 7433326.6782573 3426828.755 
7436220.1702233 
 
        SHAPEPATH "D:/webpages/indexfiles/"
 
        UNITS   meters
        PROJECTION
                "init=epsg:2393" # 2393 = YKJ 
        END

OUTPUTFORMAT
  NAME JPEG
  DRIVER "GDAL/JPEG"
  IMAGEMODE RGB
  EXTENSION "JPEG"
END

OUTPUTFORMAT
  NAME bmp
  DRIVER "GDAL/BMP"
  MIMETYPE "image/bmp"
  IMAGEMODE RGB
  EXTENSION "bmp"
  FORMATOPTION "WORLDFILE=ON"
END


# Aerial images
LAYER
        NAME    "aerial"
        GROUP   "aerial"
        TYPE    RASTER
        STATUS  DEFAULT
 
        MINSCALE 40
        MAXSCALE 50000

        PROCESSING "RESAMPLE=AVERAGE"

        PROJECTION
                "init=epsg:2393" 
        END
 
        TILEINDEX "ilmakuvat.shp"
END

LAYER
        NAME    MHGIS_GISE1_KIINTE
        DATA    data/MHGIS_GISE1_KIINTE.shp
        TYPE    LINE
        STATUS  DEFAULT
        TRANSPARENCY    0
 
 

        GROUP   UserData

    PROJECTION
      "init=epsg:2393"
    END

 
        CLASS
                STYLE
                        OUTLINECOLOR    254 255 254
                        COLOR   254 255 254
                END
        END

 
END

LAYER
        NAME    AOI
        DATA    data/AOI.shp
        TYPE    POLYGON
        STATUS  DEFAULT
 
 
 

        GROUP   UserData

    PROJECTION
      "init=epsg:2393"
    END

 
        CLASS
                STYLE
                        COLOR   0 0 255
                END
        END

 
END




END

Teemu





Stephen Woodbridge <woodbri at SWOODBRIDGE.COM>
Sent by: UMN MapServer Users List <MAPSERVER-USERS at LISTS.UMN.EDU>
28.10.2006 16:55
Please respond to Stephen Woodbridge
 
        To:     MAPSERVER-USERS at LISTS.UMN.EDU
        cc: 
        Subject:        Re: [UMN_MAPSERVER-USERS] How to create tiles 
accurately with MapServer?


Teemu Mäkelä wrote:
> 
> Hi,
> 
> I should create tiles. I have linear features and in mapfile I've 
> defined the line to be drawn with width of 1 pixel.
> 
> On the border of tiles:
> CASE A:
> - Line continues OK from tile A to tile B, if line crosses the tile 
> border with angle of 45-90 degrees.
> CASE B:
> - Line does not continue (small gap), if line crosses the tile border 
> with angle of 0-45 degrees. Gap is the problem! Size of the gap depends 
> on the angle. If angle is 5 degress, gap is about 10 pixels; if angle is 

> 30 degrees, gap is about 3 pixels.
> 
> Any idea how to get rid of the gaps on lines?
> 
> Teemu

Hi Teemu,

I think we will need more info to help. Can you post your mapfile 
please. Also how are you generating the tiles? ka-map?, mapserv cgi, 
mapscript? Are you projecting the data? How do you determine the extents 
of tile A and B?

-Steve W

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