shrug-l: Re: projections

Ann Stodola a_stodola at yahoo.com
Thu Dec 22 12:42:02 EST 2005


I also have a question about accurately RE-PROJECTING data.  Our county data uses the NAD 1927 datum, most of the state data available uses NAD 1983 or  1983 HARN.  I haven't found a predefined transformation in the ArcGIS 9.1 list that will go from either of the 1983 datums to 1927.  I have tried a couple of the choices, no success.  Any suggestions?
   
  I suppose I could transform the county data to 1983 HARN, but until we start using it consistently as the official coordinate system I don't want to get out of step with my colleagues.
   
  Thanks!
   
  Ann Stodola
  Senior Planner
  Clay County Planning Department
  PO Box 366
  Green Cove Springs, FL  32043
  ann.stodola at co.clay.fl.us
  ph: (904)269-6375
  fax: (904)529-3706
   
  shrug-l-request at lists.dep.state.fl.us wrote:
  Send SHRUG-L mailing list submissions to
shrug-l at lists.dep.state.fl.us

To subscribe or unsubscribe via the World Wide Web, visit
http://lists.dep.state.fl.us/mailman/listinfo/shrug-l
or, via email, send a message with subject or body 'help' to
shrug-l-request at lists.dep.state.fl.us

You can reach the person managing the list at
shrug-l-owner at lists.dep.state.fl.us

When replying, please edit your Subject line so it is more specific
than "Re: Contents of SHRUG-L digest..."
Today's Topics:

1. RE: Lat-Long (Thomas, Jim)
2. RE: Lat-Long (Paulsen, Janis)
3. RE: Lat-Long (Elebash, Alan)
4. RE: Lat-Long (Hughes, Ronald)
From: "Thomas, Jim" <jim_thomas at golder.com>
CC: shrug-l at lists.dep.state.fl.us
To: "Hughes, Ronald" <Ronald.Hughes at dep.state.fl.us>
Date: Thu, 22 Dec 2005 12:00:52 -0500
Subject: RE: shrug-l: Lat-Long

      

  v\:* {   BEHAVIOR: url(#default#VML)  }  o\:* {   BEHAVIOR: url(#default#VML)  }  w\:* {   BEHAVIOR: url(#default#VML)  }  .shape {   BEHAVIOR: url(#default#VML)  }      st1\:* {   BEHAVIOR: url(#default#ieooui)  }      @font-face {   font-family: Helvetica;  }  @font-face {   font-family: Wingdings;  }  @font-face {   font-family: Tahoma;  }  @page Section1 {size: 8.5in 11.0in; margin: 1.0in 1.25in 1.0in 1.25in; mso-header-margin: .5in; mso-footer-margin: .5in; mso-paper-source: 0; }  P.MsoNormal {   FONT-SIZE: 12pt; MARGIN: 0in 0in 0pt; FONT-FAMILY: "Times New Roman"; mso-style-parent: ""; mso-pagination: widow-orphan; mso-fareast-font-family: "Times New Roman"  }  LI.MsoNormal {   FONT-SIZE: 12pt; MARGIN: 0in 0in 0pt; FONT-FAMILY: "Times New Roman"; mso-style-parent: ""; mso-pagination: widow-orphan; mso-fareast-font-family: "Times New Roman"  }  DIV.MsoNormal {   FONT-SIZE: 12pt; MARGIN: 0in 0in 0pt; FONT-FAMILY: "Times New Roman"; mso-style-parent: ""; mso-pagination:
 widow-orphan; mso-fareast-font-family: "Times New Roman"  }  A:link {   COLOR: blue; TEXT-DECORATION: underline; text-underline: single  }  SPAN.MsoHyperlink {   COLOR: blue; TEXT-DECORATION: underline; text-underline: single  }  A:visited {   COLOR: purple; TEXT-DECORATION: underline; text-underline: single  }  SPAN.MsoHyperlinkFollowed {   COLOR: purple; TEXT-DECORATION: underline; text-underline: single  }  P {   FONT-SIZE: 12pt; MARGIN-LEFT: 0in; MARGIN-RIGHT: 0in; FONT-FAMILY: "Times New Roman"; mso-pagination: widow-orphan; mso-fareast-font-family: "Times New Roman"; mso-margin-top-alt: auto; mso-margin-bottom-alt: auto  }  SPAN.emailstyle18 {   COLOR: navy; FONT-FAMILY: Arial; mso-bidi-font-family: Arial; mso-style-name: emailstyle18; mso-ascii-font-family: Arial; mso-hansi-font-family: Arial  }  SPAN.EmailStyle19 {   COLOR: maroon; FONT-FAMILY: Helvetica; mso-bidi-font-family: Arial; mso-ascii-font-family: Helvetica; mso-hansi-font-family: Helvetica; mso-style-type:
 personal; mso-style-noshow: yes; mso-ansi-font-size: 10.0pt; mso-bidi-font-size: 10.0pt  }  SPAN.EmailStyle20 {   COLOR: maroon; FONT-FAMILY: Helvetica; mso-bidi-font-family: Arial; mso-ascii-font-family: Helvetica; mso-hansi-font-family: Helvetica; mso-style-type: personal; mso-style-noshow: yes; mso-ansi-font-size: 10.0pt; mso-bidi-font-size: 10.0pt  }  SPAN.EmailStyle21 {   COLOR: maroon; FONT-FAMILY: Helvetica; mso-bidi-font-family: Arial; mso-ascii-font-family: Helvetica; mso-hansi-font-family: Helvetica; mso-style-type: personal-reply; mso-style-noshow: yes; mso-ansi-font-size: 10.0pt; mso-bidi-font-size: 10.0pt  }  SPAN.SpellE {   mso-style-name: ""; mso-spl-e: yes  }  SPAN.GramE {   mso-style-name: ""; mso-gram-e: yes  }  DIV.Section1 {   page: Section1  }      In my opinion, the Export Data tool's purpose is not to be a re-projection tool, but it can re-project your data to the data frame's projection during data export.  It saves me time having to go to ArcToolbox to run a
 re-projection.  
   
  I can also troubleshoot unknown coordinate systems by changing the data frame coordinate system.  When my data lines up, I can export it to a new file using the data frames coordinate system while keeping the old file in it's original state.

    
---------------------------------
  From: Hughes, Ronald [mailto:Ronald.Hughes at dep.state.fl.us] 
Sent: Thursday, December 22, 2005 11:47 AM
To: Thomas, Jim
Cc: shrug-l at lists.dep.state.fl.us
Subject: RE: shrug-l: Lat-Long


  
    Sorry Thomas, but it doesn’t re-project.  That method you used simply re-defines the projection unless they’ve changed it in Version 9x (which is highly doubtful).  If you want to change the geometry, you’ll need to use ArcToolbox.  It’s simply isn’t good practice to assign incorrect projection files to spatial data.
   
  I hope that clears things up.
   
      
---------------------------------
  
  From: Thomas, Jim [mailto:jim_thomas at golder.com] 
Sent: Thursday, December 22, 2005 11:33 AM
To: Hughes, Ronald
Cc: shrug-l at lists.dep.state.fl.us
Subject: RE: shrug-l: Lat-Long

   
  It's not simply re-defining.  It's re-projecting.  
   
  When you use the 'Export Data...' tool from ArcMap you can select the export coordinate system (see attached jpg).  It will re-project the data to what you define.
   
  The Shruggers can use whatever method works best for them.
   
   
    
---------------------------------
  
  From: Hughes, Ronald [mailto:Ronald.Hughes at dep.state.fl.us] 
Sent: Thursday, December 22, 2005 11:23 AM
To: Thomas, Jim; shrug-l at lists.dep.state.fl.us
Subject: RE: shrug-l: Lat-Long
  Actually Thomas, the problem with that is that the NEW shapefile will still be in STATEPLANE projection.  In other words, the geometry or “physical condition” remains as STATEPLANE.  All you’ve done is re-define the projection file.  Defining a projection and actually RE-PROJECTING a shapefile are two separate things.  Re-projecting a shapefile involves changing its geometry and topology while re-defining the projection only changes a text file.  You never want to assign an incorrect projection file to a shapefile because it tends to lead to trouble if you send that file to somebody else and then they try to re-project that shapefile using incorrect projection information.  
   
  The reason that it appears to work for you is because of the ArcGIS “projection on the fly” capability.  If you were to use a GIS product that doesn’t project “on-the-fly” you would see that re-defining the projection file hasn’t changed the geometry of the shapefile: it’s still in STATEPLANE.
   
  As far as datum transformation is concerned, when switching between certain coordinate systems, you may wind up using different datum and need to transform from one datum to the next.  For example when I was using ArcGIS version 8x and projected from STATEPLANE NAD83 datum to Geographic North American 1983 HARN datum I would get the following error message:
   
  
   
  I would then have to set the transformation from NAD_1983 to HARN_Florida:
   
  
   
  Many people think that redefining the projection of a shapefile is the same and projecting a shapefile but it is not.  I hope that I’ve contributed to clearing this up.
   
  Good luck,
  Ron
   
   
      
---------------------------------
  
  From: Thomas, Jim [mailto:jim_thomas at golder.com] 
Sent: Thursday, December 22, 2005 10:52 AM
To: Hughes, Ronald; shrug-l at lists.dep.state.fl.us
Subject: RE: shrug-l: Lat-Long

   
  The steps I listed will work too.  You can export a NEW shapefile from ArcMap in the spatial reference of the data frame (which can be different than the original shapefile).  As long as everything is defined correctly, you'll have no problem.  I do it all the time.
   
  As far as the datum transformation list... that's a good question. I always wondered that.
     

     

   
    
---------------------------------
  
  From: shrug-l-bounces at lists.dep.state.fl.us [mailto:shrug-l-bounces at lists.dep.state.fl.us] On Behalf Of Hughes, Ronald
Sent: Thursday, December 22, 2005 10:32 AM
To: shrug-l at lists.dep.state.fl.us
Subject: RE: shrug-l: Lat-Long
  Actually, you need to use ArcToolbox to reproject the shapefile.  All the steps mention below do is re-define the projection file.  It would be analogous to assigning a new mailing address to you home without physically moving it from its current location.  In other words, if your house sits at 800 Main Street and you change the address to 21 Jump Street, the house still remains at 800 Main Street.  
   
  The Present version of ArcToolbox that I have (ArcGIS 9.1) is different from that what I’d previously had but it appears to work the same way.
   
  Open up ArcToolbox and select Data Management Tools à Projections and Transformations à Project. 
   
  Click on Project and a menu should come up that asks for your imput feature and output (in ArcGIS 9.1 it automatically assigns a ‘P’ at the end of the name of the input and places it in the output.  Select the projection that you want for the output by clicking on the button to the right of the input window.  That will bring up a menu called “Spatial Reference Properties”.
   
  1.) Click the button labeled “Select”.
   
  2.) Click the Geographic Coordinate Systems folder
   
  3.) Click the North America folder and select the coordinate system that you want (probably North American 1983 HARN.prj).
   
  4.) Click the “Add” button and select “OK”.
   
  If you have any other questions just ask.  
   
  Good luck!
   
  -----Original Message-----
From: shrug-l-bounces at lists.dep.state.fl.us [mailto:shrug-l-bounces at lists.dep.state.fl.us] On Behalf Of Thomas, Jim
Sent: Thursday, December 22, 2005 9:34 AM
To: tdarsey at hsa.cc; shrug-l at lists.dep.state.fl.us
Subject: RE: shrug-l: Lat-Long
   
  1. Define your shapefile's spatial reference in ArcCatalog
  2. Load the shapefile into ArcMap
  3. Change the data frame spatial reference to Lat/Long
  4. Export the new shapefile using the data frame's spatial reference (during export)
  5. That's it.
   
    
---------------------------------
  
  From: shrug-l-bounces at lists.dep.state.fl.us [mailto:shrug-l-bounces at lists.dep.state.fl.us] On Behalf Of Tony Darsey
Sent: Thursday, December 22, 2005 9:30 AM
To: shrug-l at lists.dep.state.fl.us
Subject: shrug-l: Lat-Long
    Can anyone tell me how to convert a shape file from State Plane to Lat/Long?

  Thanks, 
Tony Darsey 
HSA Consulting Group, Inc. 
1311 Executive Center Drive, Suite 255 
Tallahassee, FL 32301 
Phone (850) 309-7510 
Fax     (850) 309-7510 
Cell     (850) 508-6477 
email   tdarsey at hsa.cc 
     


From: "Paulsen, Janis" <Janis.Paulsen at dep.state.fl.us>
CC: shrug-l at lists.dep.state.fl.us
To: "Hughes, Ronald" <Ronald.Hughes at dep.state.fl.us>,
"Thomas, Jim" <jim_thomas at golder.com>
Date: Thu, 22 Dec 2005 12:03:53 -0500
Subject: RE: shrug-l: Lat-Long

              I thought I’d jump in here.  I just ran a little experiment.  I brought in two differently projected shapefiles into ArcMap 9.0. They were reprojected on the fly in ArcMap. In ArcMap, both shapefiles overlaid each other correctly.  I set the dataframe coordinate system to GCS North American NAD 83 HARN.  I did a data export on both shapefiles selecting the “use same coordinate system as data frame” option.  I then brought both shapefiles into ArcView 3.x.  The both loaded into the apr, but did not overlay eachother.  This tells me that AcrView allowed them both to be brought in because they were assigned the same coordinate system, but they were not actually reprojected geometrically, since they did not draw in the same place in space.  Interesting.
  Janis
   
  -----Original Message-----
From: shrug-l-bounces at lists.dep.state.fl.us [mailto:shrug-l-bounces at lists.dep.state.fl.us] On Behalf Of Hughes, Ronald
Sent: Thursday, December 22, 2005 11:47 AM
To: Thomas, Jim
Cc: shrug-l at lists.dep.state.fl.us
Subject: RE: shrug-l: Lat-Long
   
  Sorry Thomas, but it doesn’t re-project.  That method you used simply re-defines the projection unless they’ve changed it in Version 9x (which is highly doubtful).  If you want to change the geometry, you’ll need to use ArcToolbox.  It’s simply isn’t good practice to assign incorrect projection files to spatial data.
   
  I hope that clears things up.
   
      
---------------------------------
  
  From: Thomas, Jim [mailto:jim_thomas at golder.com] 
Sent: Thursday, December 22, 2005 11:33 AM
To: Hughes, Ronald
Cc: shrug-l at lists.dep.state.fl.us
Subject: RE: shrug-l: Lat-Long

   
  It's not simply re-defining.  It's re-projecting.  
   
  When you use the 'Export Data...' tool from ArcMap you can select the export coordinate system (see attached jpg).  It will re-project the data to what you define.
   
  The Shruggers can use whatever method works best for them.
   
   
    
---------------------------------
  
  From: Hughes, Ronald [mailto:Ronald.Hughes at dep.state.fl.us] 
Sent: Thursday, December 22, 2005 11:23 AM
To: Thomas, Jim; shrug-l at lists.dep.state.fl.us
Subject: RE: shrug-l: Lat-Long
  Actually Thomas, the problem with that is that the NEW shapefile will still be in STATEPLANE projection.  In other words, the geometry or “physical condition” remains as STATEPLANE.  All you’ve done is re-define the projection file.  Defining a projection and actually RE-PROJECTING a shapefile are two separate things.  Re-projecting a shapefile involves changing its geometry and topology while re-defining the projection only changes a text file.  You never want to assign an incorrect projection file to a shapefile because it tends to lead to trouble if you send that file to somebody else and then they try to re-project that shapefile using incorrect projection information.  
   
  The reason that it appears to work for you is because of the ArcGIS “projection on the fly” capability.  If you were to use a GIS product that doesn’t project “on-the-fly” you would see that re-defining the projection file hasn’t changed the geometry of the shapefile: it’s still in STATEPLANE.
   
  As far as datum transformation is concerned, when switching between certain coordinate systems, you may wind up using different datum and need to transform from one datum to the next.  For example when I was using ArcGIS version 8x and projected from STATEPLANE NAD83 datum to Geographic North American 1983 HARN datum I would get the following error message:
   
  
   
  I would then have to set the transformation from NAD_1983 to HARN_Florida:
   
  
   
  Many people think that redefining the projection of a shapefile is the same and projecting a shapefile but it is not.  I hope that I’ve contributed to clearing this up.
   
  Good luck,
  Ron
   
   
      
---------------------------------
  
  From: Thomas, Jim [mailto:jim_thomas at golder.com] 
Sent: Thursday, December 22, 2005 10:52 AM
To: Hughes, Ronald; shrug-l at lists.dep.state.fl.us
Subject: RE: shrug-l: Lat-Long

   
  The steps I listed will work too.  You can export a NEW shapefile from ArcMap in the spatial reference of the data frame (which can be different than the original shapefile).  As long as everything is defined correctly, you'll have no problem.  I do it all the time.
   
  As far as the datum transformation list... that's a good question. I always wondered that.
     

     

   
    
---------------------------------
  
  From: shrug-l-bounces at lists.dep.state.fl.us [mailto:shrug-l-bounces at lists.dep.state.fl.us] On Behalf Of Hughes, Ronald
Sent: Thursday, December 22, 2005 10:32 AM
To: shrug-l at lists.dep.state.fl.us
Subject: RE: shrug-l: Lat-Long
  Actually, you need to use ArcToolbox to reproject the shapefile.  All the steps mention below do is re-define the projection file.  It would be analogous to assigning a new mailing address to you home without physically moving it from its current location.  In other words, if your house sits at 800 Main Street and you change the address to 21 Jump Street, the house still remains at 800 Main Street.  
   
  The Present version of ArcToolbox that I have (ArcGIS 9.1) is different from that what I’d previously had but it appears to work the same way.
   
  Open up ArcToolbox and select Data Management Tools à Projections and Transformations à Project. 
   
  Click on Project and a menu should come up that asks for your imput feature and output (in ArcGIS 9.1 it automatically assigns a ‘P’ at the end of the name of the input and places it in the output.  Select the projection that you want for the output by clicking on the button to the right of the input window.  That will bring up a menu called “Spatial Reference Properties”.
   
  1.) Click the button labeled “Select”.
   
  2.) Click the Geographic Coordinate Systems folder
   
  3.) Click the North America folder and select the coordinate system that you want (probably North American 1983 HARN.prj).
   
  4.) Click the “Add” button and select “OK”.
   
  If you have any other questions just ask.  
   
  Good luck!
   
  -----Original Message-----
From: shrug-l-bounces at lists.dep.state.fl.us [mailto:shrug-l-bounces at lists.dep.state.fl.us] On Behalf Of Thomas, Jim
Sent: Thursday, December 22, 2005 9:34 AM
To: tdarsey at hsa.cc; shrug-l at lists.dep.state.fl.us
Subject: RE: shrug-l: Lat-Long
   
  1. Define your shapefile's spatial reference in ArcCatalog
  2. Load the shapefile into ArcMap
  3. Change the data frame spatial reference to Lat/Long
  4. Export the new shapefile using the data frame's spatial reference (during export)
  5. That's it.
   
    
---------------------------------
  
  From: shrug-l-bounces at lists.dep.state.fl.us [mailto:shrug-l-bounces at lists.dep.state.fl.us] On Behalf Of Tony Darsey
Sent: Thursday, December 22, 2005 9:30 AM
To: shrug-l at lists.dep.state.fl.us
Subject: shrug-l: Lat-Long
    Can anyone tell me how to convert a shape file from State Plane to Lat/Long?

  Thanks, 
Tony Darsey 
HSA Consulting Group, Inc. 
1311 Executive Center Drive, Suite 255 
Tallahassee, FL 32301 
Phone (850) 309-7510 
Fax     (850) 309-7510 
Cell     (850) 508-6477 
email   tdarsey at hsa.cc 
     


From: "Elebash, Alan" <Alan.Elebash at dep.state.fl.us>
To: <shrug-l at lists.dep.state.fl.us>
Date: Thu, 22 Dec 2005 12:06:25 -0500
Subject: RE: shrug-l: Lat-Long

      

  v\:* {   BEHAVIOR: url(#default#VML)  }  o\:* {   BEHAVIOR: url(#default#VML)  }  w\:* {   BEHAVIOR: url(#default#VML)  }  .shape {   BEHAVIOR: url(#default#VML)  }      st1\:* {   BEHAVIOR: url(#default#ieooui)  }      @font-face {   font-family: Helvetica;  }  @font-face {   font-family: Wingdings;  }  @font-face {   font-family: Tahoma;  }  @page Section1 {size: 8.5in 11.0in; margin: 1.0in 1.25in 1.0in 1.25in; mso-header-margin: .5in; mso-footer-margin: .5in; mso-paper-source: 0; }  P.MsoNormal {   FONT-SIZE: 12pt; MARGIN: 0in 0in 0pt; FONT-FAMILY: "Times New Roman"; mso-style-parent: ""; mso-pagination: widow-orphan; mso-fareast-font-family: "Times New Roman"  }  LI.MsoNormal {   FONT-SIZE: 12pt; MARGIN: 0in 0in 0pt; FONT-FAMILY: "Times New Roman"; mso-style-parent: ""; mso-pagination: widow-orphan; mso-fareast-font-family: "Times New Roman"  }  DIV.MsoNormal {   FONT-SIZE: 12pt; MARGIN: 0in 0in 0pt; FONT-FAMILY: "Times New Roman"; mso-style-parent: ""; mso-pagination:
 widow-orphan; mso-fareast-font-family: "Times New Roman"  }  A:link {   COLOR: blue; TEXT-DECORATION: underline; text-underline: single  }  SPAN.MsoHyperlink {   COLOR: blue; TEXT-DECORATION: underline; text-underline: single  }  A:visited {   COLOR: purple; TEXT-DECORATION: underline; text-underline: single  }  SPAN.MsoHyperlinkFollowed {   COLOR: purple; TEXT-DECORATION: underline; text-underline: single  }  P {   FONT-SIZE: 12pt; MARGIN-LEFT: 0in; MARGIN-RIGHT: 0in; FONT-FAMILY: "Times New Roman"; mso-pagination: widow-orphan; mso-fareast-font-family: "Times New Roman"; mso-margin-top-alt: auto; mso-margin-bottom-alt: auto  }  SPAN.emailstyle18 {   COLOR: navy; FONT-FAMILY: Arial; mso-bidi-font-family: Arial; mso-style-name: emailstyle18; mso-ascii-font-family: Arial; mso-hansi-font-family: Arial  }  SPAN.EmailStyle19 {   COLOR: maroon; FONT-FAMILY: Helvetica; mso-bidi-font-family: Arial; mso-ascii-font-family: Helvetica; mso-hansi-font-family: Helvetica; mso-style-type:
 personal; mso-style-noshow: yes; mso-ansi-font-size: 10.0pt; mso-bidi-font-size: 10.0pt  }  SPAN.EmailStyle20 {   COLOR: maroon; FONT-FAMILY: Helvetica; mso-bidi-font-family: Arial; mso-ascii-font-family: Helvetica; mso-hansi-font-family: Helvetica; mso-style-type: personal; mso-style-noshow: yes; mso-ansi-font-size: 10.0pt; mso-bidi-font-size: 10.0pt  }  SPAN.EmailStyle21 {   COLOR: maroon; FONT-FAMILY: Helvetica; mso-bidi-font-family: Arial; mso-ascii-font-family: Helvetica; mso-hansi-font-family: Helvetica; mso-style-type: personal-reply; mso-style-noshow: yes; mso-ansi-font-size: 10.0pt; mso-bidi-font-size: 10.0pt  }  SPAN.SpellE {   mso-style-name: ""; mso-spl-e: yes  }  SPAN.GramE {   mso-style-name: ""; mso-gram-e: yes  }  DIV.Section1 {   page: Section1  }      This is from ArcGIS 9.1 help:
   
  About saving data to a new projection   When you export data from ArcMap, you can choose to create a new   




feature class using a different coordinate system than that of the source data, use the   




coordinate system of the   




data frame, or use the coordinate system of the   




feature dataset to which you are exporting the data.   
  
In ArcCatalog, when you export data to a feature dataset in a geodatabase, it will use the coordinate system of the feature dataset. If you export data as a standalone feature class or to a file-based data source, it will have the same coordinate system as the source data.   
  
The ArcToolbox   


Project tool allows you to make a copy of your data and change its coordinate system. This tool changes the coordinate system of the data and transforms the shapes in the data to use the new coordinate system. You can use the Project tool as part of a model or as you need it while working in ArcMap or ArcCatalog.   
  
If your data's   




geographic coordinate system uses a different   




datum than that of the new feature class, you will likely write spatially inaccurate data. Instead of directly writing to the new feature class, make a copy of the original feature class and use the Project tool to reproject that feature class to the coordinate system that you ultimately want to use. As part of using the Project tool, you will be able to specify a datum transformation. Once you have projected the copy, you can copy it into the new workspace and delete the first copy. This applies to any place in ArcMap or a geoprocessing tool that is able to write new data. 

   
   
  Hope this helps.
  Alan Elebash 
GIS Analyst 
Office of Park Planning 
Division of Recreation and Parks 
850  245-3051 
  Florida State Parks - the "Real Florida" 
www.floridastateparks.org 
From: "Hughes, Ronald" <Ronald.Hughes at dep.state.fl.us>
CC: shrug-l at lists.dep.state.fl.us
To: "Paulsen, Janis" <Janis.Paulsen at dep.state.fl.us>,
"Thomas, Jim" <jim_thomas at golder.com>
Date: Thu, 22 Dec 2005 12:07:43 -0500
Subject: RE: shrug-l: Lat-Long

      

    v\:* {behavior:url(#default#VML);}  o\:* {behavior:url(#default#VML);}  w\:* {behavior:url(#default#VML);}  .shape {behavior:url(#default#VML);}        st1\:*{behavior:url(#default#ieooui) }                Thank you Janis.  This is the point I was making.  As I’d mentioned previously, it is the “on the fly projection” in ArcGIS that makes them to overlay, but as you pointed out, when you use a product that doesn’t have “on the fly projection” you see that the geometry didn’t change.  Only the projection definition changed.
   
      
---------------------------------
  
  From: Paulsen, Janis 
Sent: Thursday, December 22, 2005 12:04 PM
To: Hughes, Ronald; Thomas, Jim
Cc: shrug-l at lists.dep.state.fl.us
Subject: RE: shrug-l: Lat-Long

   
  I thought I’d jump in here.  I just ran a little experiment.  I brought in two differently projected shapefiles into ArcMap 9.0. They were reprojected on the fly in ArcMap. In ArcMap, both shapefiles overlaid each other correctly.  I set the dataframe coordinate system to GCS North American NAD 83 HARN.  I did a data export on both shapefiles selecting the “use same coordinate system as data frame” option.  I then brought both shapefiles into ArcView 3.x.  The both loaded into the apr, but did not overlay eachother.  This tells me that AcrView allowed them both to be brought in because they were assigned the same coordinate system, but they were not actually reprojected geometrically, since they did not draw in the same place in space.  Interesting.
  Janis
   
  -----Original Message-----
From: shrug-l-bounces at lists.dep.state.fl.us [mailto:shrug-l-bounces at lists.dep.state.fl.us] On Behalf Of Hughes, Ronald
Sent: Thursday, December 22, 2005 11:47 AM
To: Thomas, Jim
Cc: shrug-l at lists.dep.state.fl.us
Subject: RE: shrug-l: Lat-Long
   
  Sorry Thomas, but it doesn’t re-project.  That method you used simply re-defines the projection unless they’ve changed it in Version 9x (which is highly doubtful).  If you want to change the geometry, you’ll need to use ArcToolbox.  It’s simply isn’t good practice to assign incorrect projection files to spatial data.
   
  I hope that clears things up.
   
        
---------------------------------
  

  From: Thomas, Jim [mailto:jim_thomas at golder.com] 
Sent: Thursday, December 22, 2005 11:33 AM
To: Hughes, Ronald
Cc: shrug-l at lists.dep.state.fl.us
Subject: RE: shrug-l: Lat-Long

   
  It's not simply re-defining.  It's re-projecting.  
   
  When you use the 'Export Data...' tool from ArcMap you can select the export coordinate system (see attached jpg).  It will re-project the data to what you define.
   
  The Shruggers can use whatever method works best for them.
   
   
      
---------------------------------
  

  From: Hughes, Ronald [mailto:Ronald.Hughes at dep.state.fl.us] 
Sent: Thursday, December 22, 2005 11:23 AM
To: Thomas, Jim; shrug-l at lists.dep.state.fl.us
Subject: RE: shrug-l: Lat-Long
  Actually Thomas, the problem with that is that the NEW shapefile will still be in STATEPLANE projection.  In other words, the geometry or “physical condition” remains as STATEPLANE.  All you’ve done is re-define the projection file.  Defining a projection and actually RE-PROJECTING a shapefile are two separate things.  Re-projecting a shapefile involves changing its geometry and topology while re-defining the projection only changes a text file.  You never want to assign an incorrect projection file to a shapefile because it tends to lead to trouble if you send that file to somebody else and then they try to re-project that shapefile using incorrect projection information.  
   
  The reason that it appears to work for you is because of the ArcGIS “projection on the fly” capability.  If you were to use a GIS product that doesn’t project “on-the-fly” you would see that re-defining the projection file hasn’t changed the geometry of the shapefile: it’s still in STATEPLANE.
   
  As far as datum transformation is concerned, when switching between certain coordinate systems, you may wind up using different datum and need to transform from one datum to the next.  For example when I was using ArcGIS version 8x and projected from STATEPLANE NAD83 datum to Geographic North American 1983 HARN datum I would get the following error message:
   
  
   
  I would then have to set the transformation from NAD_1983 to HARN_Florida:
   
  
   
  Many people think that redefining the projection of a shapefile is the same and projecting a shapefile but it is not.  I hope that I’ve contributed to clearing this up.
   
  Good luck,
  Ron
   
   
        
---------------------------------
  

  From: Thomas, Jim [mailto:jim_thomas at golder.com] 
Sent: Thursday, December 22, 2005 10:52 AM
To: Hughes, Ronald; shrug-l at lists.dep.state.fl.us
Subject: RE: shrug-l: Lat-Long

   
  The steps I listed will work too.  You can export a NEW shapefile from ArcMap in the spatial reference of the data frame (which can be different than the original shapefile).  As long as everything is defined correctly, you'll have no problem.  I do it all the time.
   
  As far as the datum transformation list... that's a good question. I always wondered that.
     

     

   
      
---------------------------------
  

  From: shrug-l-bounces at lists.dep.state.fl.us [mailto:shrug-l-bounces at lists.dep.state.fl.us] On Behalf Of Hughes, Ronald
Sent: Thursday, December 22, 2005 10:32 AM
To: shrug-l at lists.dep.state.fl.us
Subject: RE: shrug-l: Lat-Long
  Actually, you need to use ArcToolbox to reproject the shapefile.  All the steps mention below do is re-define the projection file.  It would be analogous to assigning a new mailing address to you home without physically moving it from its current location.  In other words, if your house sits at 800 Main Street and you change the address to 21 Jump Street, the house still remains at 800 Main Street.  
   
  The Present version of ArcToolbox that I have (ArcGIS 9.1) is different from that what I’d previously had but it appears to work the same way.
   
  Open up ArcToolbox and select Data Management Tools à Projections and Transformations à Project. 
   
  Click on Project and a menu should come up that asks for your imput feature and output (in ArcGIS 9.1 it automatically assigns a ‘P’ at the end of the name of the input and places it in the output.  Select the projection that you want for the output by clicking on the button to the right of the input window.  That will bring up a menu called “Spatial Reference Properties”.
   
  1.) Click the button labeled “Select”.
   
  2.) Click the Geographic Coordinate Systems folder
   
  3.) Click the North America folder and select the coordinate system that you want (probably North American 1983 HARN.prj).
   
  4.) Click the “Add” button and select “OK”.
   
  If you have any other questions just ask.  
   
  Good luck!
   
  -----Original Message-----
From: shrug-l-bounces at lists.dep.state.fl.us [mailto:shrug-l-bounces at lists.dep.state.fl.us] On Behalf Of Thomas, Jim
Sent: Thursday, December 22, 2005 9:34 AM
To: tdarsey at hsa.cc; shrug-l at lists.dep.state.fl.us
Subject: RE: shrug-l: Lat-Long
   
  1. Define your shapefile's spatial reference in ArcCatalog
  2. Load the shapefile into ArcMap
  3. Change the data frame spatial reference to Lat/Long
  4. Export the new shapefile using the data frame's spatial reference (during export)
  5. That's it.
   
      
---------------------------------
  

  From: shrug-l-bounces at lists.dep.state.fl.us [mailto:shrug-l-bounces at lists.dep.state.fl.us] On Behalf Of Tony Darsey
Sent: Thursday, December 22, 2005 9:30 AM
To: shrug-l at lists.dep.state.fl.us
Subject: shrug-l: Lat-Long
    Can anyone tell me how to convert a shape file from State Plane to Lat/Long?

  Thanks, 
Tony Darsey 
HSA Consulting Group, Inc. 
1311 Executive Center Drive, Suite 255 
Tallahassee, FL 32301 
Phone (850) 309-7510 
Fax     (850) 309-7510 
Cell     (850) 508-6477 
email   tdarsey at hsa.cc 
     


_______________________________________________
SHRUG-L mailing list
SHRUG-L at lists.dep.state.fl.us
http://lists.dep.state.fl.us/mailman/listinfo/shrug-l
  


		
---------------------------------
Yahoo! for Good - Make a difference this year. 
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.dep.state.fl.us/pipermail/shrug-l/attachments/20051222/ebdda789/attachment.htm


More information about the SHRUG-L mailing list