[mapserver-users] projection problem

[Gerry Creager N5JXS]

WGS84  is the correct datum for GPS data (assuming your GPS didn't
diddle them for you: not all 3 param transforms in the lowcost receivers
are created equally), and GRS80 is the definitive ellipsoid for WGS84.

These could well cause your problem.

A transformation of the basemap data to NAD83 would yield a much better
fit, as it's clinically indistinguishable from WGS84 save at the lowest
levels.

gerry
--
David Armstrong wrote:
> 
> Could someone on the list please check the attached map file
> for whatever reason i am unable to get the gps layer projection to work , am
> i missing some crucial entrys
> the map layer appears to work ok but not able to overlay the GPS  wgs84
> layer
> This is driving me nuts!
> 
> Regards
> Dave
> 
> <>--- map file -----<>
> 
> map
> 
> extent 2768239.002073439 504002.5248415045 3462077.742742627
> 895960.5502721686
> 
> # extent 2929104.53692815 -534387.296051676
> 3296713.81437212 -864213.337652181
> 
> imagecolor 255 255 255
> 
> name "FINAL"
> 
> shapepath "data"
> 
> size 600 600
> 
> status on
> 
> # SYMBOLSET "symbols\all.sym"
> 
> SYMBOLSET "symbols\symbols.sym"
> 
> #set map output to projection required
> 
> #note that extents need to be set to the same as the output map projection
> 
> # not needed here as the map is the same as the output map projection
> required
> 
> # 4204: texas south central: nad27
> 
> PROJECTION
> 
> proj=lcc
> 
> lat_1=28.383333333
> 
> lat_2=30.283333333
> 
> lat_0=27.833333333
> 
> lon_0=-99.000000000
> 
> x_0=609601.219
> 
> y_0=0.000
> 
> ellps=clrk66
> 
> datum=NAD27
> 
> to_meter=0.3048006096
> 
> END #end projection
> 
> # 1 scalebar #none
> 
> scalebar
> 
> backgroundcolor 255 255 0
> 
> color 255 255 255
> 
> imagecolor 255 255 255
> 
> intervals 4
> 
> outlinecolor 0 0 0
> 
> size 200 7
> 
> status on
> 
> style 0
> 
> transparent true
> 
> units feet
> 
> # 1 label #none
> 
> label
> 
> backgroundcolor 0 0 0
> 
> color 255 255 0
> 
> size tiny
> 
> end
> 
> end
> 
> # 2 layer Grant
> 
> LAYER
> 
> # CLASSITEM "ContractID"
> 
> DATA Grant
> 
> GROUP Grant
> 
> # LABELCACHE on
> 
> # LABELITEM "ContractID"
> 
> NAME Grant
> 
> # POSTLABELCACHE true
> 
> STATUS ON
> 
> TYPE POINT
> 
> #set projection of gps , note that this needs to be wgs84 in decimal degrees
> for gps
> 
> #WGS84 Decimal Degrees (EPSG 4326)
> 
> PROJECTION
> 
> proj=latlong
> 
> datum=WGS84
> 
> END
> 
> # 1 class Grant_1
> 
> CLASS
> 
> BACKGROUNDCOLOR 128 128 128
> 
> SYMBOL "circle"
> 
> SIZE 16
> 
> COLOR 110 110 128
> 
> NAME 'Grant_1'
> 
> OUTLINECOLOR 0 0 0
> 
> END
> 
> END
> 
> # 3 layer roadharr_orig
> 
> layer
> 
> classitem "FNODE_"
> 
> data "roadharr_orig"
> 
> group "roadharr_orig"
> 
> labelcache on
> 
> labelitem "FNODE_"
> 
> name "roadharr_orig"
> 
> postlabelcache true
> 
> status on
> 
> type line
> 
> #set projection of map layer,
> 
> #not sure if we need this as the map is the same as the output map
> 
> # we should get away with setting the output map projection and only the gps
> layer
> 
> #NAD_1927_Stateplane_Texas_South_Central_Fips_4204
> 
> PROJECTION
> 
> proj=lcc
> 
> lat_1=28.383333333
> 
> lat_2=30.283333333
> 
> lat_0=27.833333333
> 
> lon_0=-99.000000000
> 
> x_0=609601.219
> 
> y_0=0.000
> 
> ellps=clrk66
> 
> datum=NAD27
> 
> to_meter=0.3048006096
> 
> END
> 
> # 1 class roadharr_orig_1
> 
> class
> 
> backgroundcolor 128 128 128
> 
> color 128 128 128
> 
> name "roadharr_orig_1"
> 
> outlinecolor 0 0 0
> 
> end
> 
> end
> 
> # 4 web FINAL.html
> 
> web
> 
> footer "FINAL_footer.html"
> 
> header "FINAL_header.html"
> 
> imagepath "c:\phpdev\www\tmp\"
> 
> imageurl "/tmp/"
> 
> template "FINAL.html"
> 
> end
> 
> # 5 querymap hilite
> 
> querymap
> 
> color 255 0 0
> 
> size 200 200
> 
> status on
> 
> style hilite
> 
> end
> 
> # 6 reference graphics/reference.gif
> 
> reference
> 
> color -1 -1 -1
> 
> extent 2768239.002073439 504002.5248415045 3462077.742742627
> 895960.5502721686
> 
> #extent 2929104.53693 534387.296052 3296713.81437 952327.2342
> 
> image "graphics/reference.gif"
> 
> outlinecolor 255 0 0
> 
> size 120 120
> 
> status on
> 
> end
> 
> # 7 legend #none
> 
> legend
> 
> keysize 18 12
> 
> status on
> 
> # 1 label #none
> 
> label
> 
> color 0 0 89
> 
> size medium
> 
> type bitmap
> 
> end
> 
> end
> 
> end
> 
> <> end map file <>

--
Gerry Creager -- gerry at cs.tamu.edu
Network Engineering
Academy for Advanced Telecommunications and Learning Technologies		
Texas A&M University	979.458.4020  (Phone) -- 979.847.8578  (Fax)