Just trying to get a better understanding.

[Ethan Alpert]

http://www.esri.com/library/whitepapers/pdfs/shapefile.pdf




-----Original Message-----
From: UMN MapServer Users List [mailto:MAPSERVER-USERS at LISTS.UMN.EDU] On
Behalf Of Joseph Norris
Sent: Tuesday, December 07, 2004 5:16 PM
To: MAPSERVER-USERS at LISTS.UMN.EDU
Subject: Re: [UMN_MAPSERVER-USERS] Just trying to get a better
understanding.


Ethan,

What I have are two layers one with the zip California file and I was
able to place another layer of points over it using the utility fGIS.  I
there is no relation at all then how does the point shape file know that
it should be putting its points over a specific place in the zip shape
file?


#Joseph Norris (Perl - what else is there?/Linux/CGI/Mysql) print @c=map
chr
$_+100,(6,17,15,16,-68,-3,10,11,16,4,1,14,-68,12,1,14,8,-68,4,-3,-1,7,1,
14,-
68,-26,11,15,1,12,4,-68,-22,11,14,14,5,15,-90);

-----Original Message-----
From: Ethan Alpert [mailto:ealpert at digitalglobe.com]
Sent: Tuesday, December 07, 2004 4:04 PM
To: Joseph Norris; MAPSERVER-USERS at LISTS.UMN.EDU
Subject: RE: [UMN_MAPSERVER-USERS] Just trying to get a better
understanding.


The contents of the dbf file is just attributes for the shapes. They
have no meaning what-so-ever with respect to mapping the data. Whoever
wrote the dbf file decided to put the coordinates of the point into the
dbf.

-e

-----Original Message-----
From: UMN MapServer Users List [mailto:MAPSERVER-USERS at LISTS.UMN.EDU] On
Behalf Of Joseph Norris
Sent: Tuesday, December 07, 2004 4:03 PM
To: MAPSERVER-USERS at LISTS.UMN.EDU
Subject: [UMN_MAPSERVER-USERS] Just trying to get a better
understanding.


I have this simple shapefile:

File Bounds: ( 6471392.899,  282843.628,0,0)
         to  ( 8433025.828, 2304680.124,0,0)

Shape:0 (Point)  nVertices=1, nParts=0
  Bounds:( 7750718.722, 1391592.674, 0, 0)
      to ( 7750718.722, 1391592.674, 0, 0)
     ( 7750718.722, 1391592.674, 0, 0)

Shape:1 (Point)  nVertices=1, nParts=0
  Bounds:( 6471392.899, 2304680.124, 0, 0)
      to ( 6471392.899, 2304680.124, 0, 0)
     ( 6471392.899, 2304680.124, 0, 0)

Shape:2 (Point)  nVertices=1, nParts=0
  Bounds:( 8433025.828,  282843.628, 0, 0)
      to ( 8433025.828,  282843.628, 0, 0)
     ( 8433025.828,  282843.628, 0, 0)

Shape:3 (Point)  nVertices=1, nParts=0
  Bounds:( 6862716.092, 1226032.862, 0, 0)
      to ( 6862716.092, 1226032.862, 0, 0)
     ( 6862716.092, 1226032.862, 0, 0)

Shape:4 (Point)  nVertices=1, nParts=0
  Bounds:( 7249022.321, 1677559.623, 0, 0)
      to ( 7249022.321, 1677559.623, 0, 0)
     ( 7249022.321, 1677559.623, 0, 0)

And it relates to this dbf file:

7750718.72:1391592.67:Fred Flinstone
6471392.9:2304680.12:Jeff Jackson
8433025.83:282843.63:Trueman Polygonas 6862716.09:1226032.86:Alfred
Espinoza 7249022.32:1677559.62:Jim Apple

I can bring this layer into place over my main map file and I see the
points. What I do not see is the relationship between the xy coordinates
in the dbf file and the Bounds in the shape file.

Can someone give me an understanding of this?

Thanks.


#Joseph Norris (Perl - what else is there?/Linux/CGI/Mysql) print @c=map
chr
$_+100,(6,17,15,16,-68,-3,10,11,16,4,1,14,-68,12,1,14,8,-68,4,-3,-1,7,1,
14,-
68,-26,11,15,1,12,4,-68,-22,11,14,14,5,15,-90);