GIS-T 2008 CAD/GIS Integration in Transportation Projects

Vince Hamilton
GIS-T 2008
CAD/GIS Integration in
Transportation Projects
Presented By: Vince Hamilton
Vince Hamilton
You send your spouse to buy an oil pump…
Vince Hamilton
Quick Overview
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Why are they different?
What you have to know to line them up
How to determine your coordinate system
What are Projection Files?
What are World Files?
Surface to Grid Transformation
Finding your combined scale factor
How to line up a CAD file in GIS
How to line up a GIS file in CAD
Vince Hamilton
Why are they different?
The world is not flat and it not exactly round
either. There are different definitions of
the curvature of the earth based on where
you are. The curvature at the equator is
much different than it is at the north or
south poles. When an engineering project
is surveyed, the surveyors create an
accurate description of a small area and
tie it to an established curvature definition
that is the most accurate for their locale.
Vince Hamilton
Looking at the “iods”
Vince Hamilton
What do you have to know to line
up your files?
• First you must know the projection, datum
and scale factor of the file to be matched.
• Second you must know the projection,
datum, and scale factor of the file your are
matching.
That’s all you need!
Vince Hamilton
Learn your coordinate systems
Vince Hamilton
Latitude and Longitude
Degrees,
Minutes, and
Seconds
31° 52’ 01”
Decimal
Degrees
31.8706
Vince Hamilton
What is a Projection file
PROJCS["NAD_1983_StatePlane_Texas_South_Central_FIPS_4204_Feet",
GEOGCS["GCS_North_American_1983",
DATUM["D_North_American_1983",
SPHEROID["GRS_1980",6378137.0,298.257222101]],
PRIMEM["Greenwich",0.0],
UNIT["Degree",0.0174532925199433]],
PROJECTION["Lambert_Conformal_Conic"],
PARAMETER["False_Easting",1968500.0],
PARAMETER["False_Northing",13123333.33333333],
PARAMETER["Central_Meridian",-99.0],
PARAMETER["Standard_Parallel_1",28.38333333333333],
PARAMETER["Standard_Parallel_2",30.28333333333333],
PARAMETER["Latitude_Of_Origin",27.83333333333333],
UNIT["Foot_US",0.3048006096012192]]
Vince Hamilton
Check the Metadata
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Spatial_Reference_Information:
– Horizontal_Coordinate_System_Definition:
• Planar:
– Map_Projection:
» Map_Projection_Name: Lambert Conformal Conic
» Lambert_Conformal_Conic:
» Standard_Parallel: 28.383333
» Standard_Parallel: 30.283333
» Longitude_of_Central_Meridian: -99.000000
» Latitude_of_Projection_Origin: 27.833333
» False_Easting: 1968500.000000
» False_Northing: 13123333.333333
• Planar_Coordinate_Information:
– Planar_Coordinate_Encoding_Method: coordinate pair
– Coordinate_Representation:
» Abscissa_Resolution: 0.001024
» Ordinate_Resolution: 0.001024
– Planar_Distance_Units: survey feet
– Geodetic_Model:
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Horizontal_Datum_Name: North American Datum of 1983
Ellipsoid_Name: Geodetic Reference System 80
Semi-major_Axis: 6378137.000000
Denominator_of_Flattening_Ratio: 298.257222
Vince Hamilton
Images use World Files
The file extensions can be *.tfw,ttw,wld
1.00000000000000
0.00000000000000
0.00000000000000
-1.00000000000000
3120402.69902200019000
13845141.00324700028000
Line 1: (A) X scale in resulting X direction
Line 2: (B) Y scale in resulting X direction
Line 3: (C) X scale in resulting Y direction
Line 4: (D) Y scale in resulting Y direction
Line 5: (E) X coordinate of the center of the center of rotation(the center of the Upper Left Pixel of the unrotated image)
Line 6: (F) Y coordinate of the center of the center of rotation(the center of the Upper Left Pixel of the unrotated image)
or in algebraic form
X' = (A*X) + (B*Y) + E Y' = (C*X) + (D*Y) + F
where X’ and Y’ are georeferenced coordinates and
x is pixel columns and y is pixels rows
D is negative because pixel rows increase opposite an increasing
northing direction.
B and C are zero for unrotated and unsheared georeferences
A and D are zero for 90 and 270 degree rotations
world file ax + by center for more references
Vince Hamilton
How projections are handled in GIS
When you create a map in ESRI you must
define the map projection. The ESRI
software uses the projection files to
“project” the data to match your map “on
the fly”. If the map is in NAD83 and you
attach a data set that is in NAD27, the
software will automatically “re-project” the
data to NAD83 without writing it out to a
new file.
Vince Hamilton
CAD files have projections too
When a CAD file is added to GIS using the CAD feature class in white,
a projection will be applied if a .prj file exists with the same name as the CAD file.
The CAD symbology will also be applied to the GIS layer.
The .prj files are being phased out and replaced with XML files that contain the
Metadata for each file.
Vince Hamilton
One for ALL and ALL for One
If all of the CADD files in the same folder
have the same projection, then you can
use a single projection file. Create the
projection file and then rename it to
ESRI_CAD.prj. The GIS software will use
this projection for all of the CADD files in
that folder.
Vince Hamilton
Use ArcCatalog to define or
create a projection
Vince Hamilton
Selecting an existing projection
Vince Hamilton
Vince Hamilton
Texas State Mapping System
Shakleford Projection
System Name
Projection
Spheriod
Datum
Central Meridian
Reference Latitude
Standard Parallel 1
Standard Parallel 2
False Easting (Meters)
False Northing (Meters)
Units
Texas State Mapping System
(Shakleford)
Lambert Conformal Conic
GRS80
NAD83
-100
31.16667
27.41667
34.91667
1000000
1000000
Meters
Vince Hamilton
Texas Centric Mapping System
System Name
Projection
Spheriod
Datum
Central Meridian
Reference Latitude
Standard Parallel 1
Standard Parallel 2
False Easting (Meters)
False Northing (Meters)
Units
Texas Centric Mapping
System/Lambert
Conformal(TCMS/LC)
Lambert Conformal Conic
GRS80
NAD83
-100
18
27.5
35
1500000
5000000
Meters
Texas Centric Mapping
System/Albers Equal
Area(TCMS/AEA)
Albers Equal Area Conic
GRS80
NAD83
-100
18
27.5
35
1500000
6000000
Meters
Vince Hamilton
Create each Texas Coordinate System
You can simply
copy the resulting
.prj file to the
same name as
the CAD file and
the GIS software
will use it. For
example the CAD
file BW8E.DGN
would have a
corresponding
BW8E.PRJ file.
.
Vince Hamilton
The coordinate systems are right
but they still don’t line up
This is due to the fact that engineering
surveys use ground surface coordinates
and GIS uses the projection grid.
Vince Hamilton
Don’t make that move!
You cannot simply move a CAD file from surface to grid
coordinates, it must be scaled. It must be scaled from
0,0 so that the combined scale factor is applied across
the entire projected grid. The TxDOT district 12
standard scale factor is 1.00013. This does not seem
like a very large number, but the Texas NAD 83
coordinates in the Houston area are in the neighborhood
of 7,000,000 in the X and 13,000,000 in the Y. That is
roughly 90 feet in the X and 1,690 in the Y direction.
Note that this conversion is from grid to surface, we want
to go the other way so you use the reciprocal value of
.99987 to scale an engineering CAD file down to the GIS
grid coordinates.
Vince Hamilton
CAD file without surface to grid
scale factor applied
Vince Hamilton
CAD file in GIS after applying the
surface to grid scale factor
Vince Hamilton
Where do I get the Scale Factor?
The engineering plan sets will have the
scale factor on either the title sheet, the
general notes sheet or the geometric
layout sheet.
TxDOT has assigned scale factors for each
county and that information is on the
following pages.
Vince Hamilton
Zone 4201 North Zone
County
Surface Adjustment Factor
Armstrong
1.00019
Brisco
1.00009
Carson
1.00019
Castro
1.00013
Childress
1.00009
Collinsworth
1.00019
Dallam
1.00013
Deaf Smith
1.00019
Donlev
1.00019
Grav
1.00019
Hall
1.00009
Hansford
1.00013
Hartley
1.00019
Hemphill
1.00019
Hutchison
1.00019
Lipscomb
1.00013
Moore
1.00019
Ochiltree
1.00013
Oldham
1.00019
Parmer
1.00013
Potter
1.00019
Randall
1.00019
Roberts
1.00019
Sherman
1.00013
Swisher
1.00013
Wheeler
1.00019
Vince Hamilton
Zone 4202 North Central Zone
County
Andrews
Archer
Bailey
Baylor
Borden
Bowie
Callahan
Camp
Cass
Clay
Cochran
Collin
Cooke
Cottle
Crosby
Dallas
Dawson
Delta
Denton
Dickens
Eastland
Ellis
Erath
Fannin
Fisher
Floyd
Foard
Franklin
Gaines
Garza
Grayson
Gregg
Hale
Hardeman
Harrison
Haskall
Henderson
Hill
Hockley
Surface Adjustment Factor
1.00021
1.00012
1.00012
1.00012
1.00021
1.00012
1.00012
1.00012
1.00012
1.00006
1.00021
1.00012
1.00012
1.00006
1.00021
1.00012
1.00021
1.00012
1.00012
1.00021
1.00012
1.00006
1.00006
1.00012
1.00021
1.00009
1.00006
1.00012
1.00021
1.00021
1.00012
1.00012
1.00012
0.99994
1.00012
1.00012
1.00006
0.999976
1.00021
County
Hood
Hopkins
Howard
Hunt
Jack
Johnson
Jones
Kaufman
Kent
King
Knox
Lamar
Lamb
Lubbock
Lynn
Marion
Martin
Mitchell
Montague
Morrls
Motley
Navarro
Nolan
Palo Pinto
Panola
Parker
Rains
Red River
Rockwall
Rusk
Scurry
Shackleford
Smith
Somervell
Stephens
Stonewall
Tarrant
Taylor
Terry
Surface Adjustment Factor
1.00012
1.00012
1.00012
1.00012
1.00012
1.00012
1.00012
1.00012
1.00021
1.00012
1.00012
1.00012
1.00012
1.00011
1.00021
1.00012
1.00021
1.00012
1.00012
1.00012
1.00008
0.999976
1.00012
1.00012
1.00006
1.00012
1.00012
1.00012
1.00012
0.999976
1.00021
1.00012
1.00012
1.00006
1.00012
1.00021
1.00012
1.00012
1.00021
County
Throckmorton
Titus
Upshur
Van Zandt
Wichita
Wilbarger
Wise
Wood
Yoakum
Young
Surface Adjustment Factor
1.00012
1.00012
1.00012
1.00012
1.00006
0.999976
1.00012
1.00012
1.00021
1.00012
Vince Hamilton
Zone 4203 Central Zone
County
Surface Adjustment Factor
Anderson
1.00003
Angelina
1.00012
Bastrop
1.00003
Bell
1.00012
Blanco
1.0001
Bosque
1.00003
Brazos
1.00012
Brown
1.0001
Burleson
1.00012
Burnet
1.00012
Cherokee
1.00003
Coke
1.00012
Coleman
1.0001
Comanche
1.00003
Concho
1.0002
Coryell
1.00012
Crane
1.0002
Crockett
1.0002
Culberson
1.00025
Ector
1.00012
EI Paso
1.000181733
Falls
1.00011
Freestone
1.00003
Gillespie
1.00012
Glasscock
1.00012
Grimes
1.00012
Hamilton
1.00001
Hardin
1.00003
Houston
1.00012
Hudspeth
1.00025
Irion
1.0002
Jasper
1.00012
Jeff Davis
1.0002
Kimble
1.00012
Lampasas
1.00012
Lee
1.00003
Leon
1.00012
Liberty
1.00003
Limestone
1.00012
County
Surface Adjustment Factor
Llano
1.00012
Loving
1.00012
Madison
1.00012
Mason
1.00012
McCulloch
1.00012
McLennan
1.00012
Menard
1.0002
Midland
1.00012
Milam
1.00012
Millis
1.00012
Montgomery
1.00003
Nacogdoche
1.00012
Newton
1.00012
Orange
1.00003
Pecos
1.0002
Polk
1.00012
Reagan
1.0002
Reeves
1.0002
Robertson
1.00012
Runnels
1.00012
Sabine
1.00012
San Augusti
1.00012
San Jacinto
1.00012
San Saba
1.00012
Schleicher
1.0002
Shelby
1.00003
Sterling
1.00012
Sutton
1.00012
Tom Green
1.0002
Travis
1.0001
Trinity
1.00012
Tyler
1.00012
Upton
1.0002
Walker
1.00012
Ward
1.0002
Washington
1.00003
Williamson
1.00012
Winkler
1.00012
Vince Hamilton
Zone 4204 South Central Zone
County
Surface Adjustment Factor
Aransas
0.999894
Atascosa
1.00013
Austin
1.00013
Bandera
1.00013
Bee
1
Bexar
1.00013
Brazoria
1.00013
Brewster
1.0002
Caldwell
1.00013
Calhoun
1
Chambers
1.00013
Colorado
1.00013
Comal
1.00013
DeWitt
1.00013
Dlmmit
1
Edwards
1.00013
Fayette
1.00013
Fort Bend
1.00013
Frio
1.00013
Galveston
1.00013
Gollad
1.00007
Gonzales
1.00013
Guadalupe
1.00013
Harris
1.00013
Hays
1.00013
Jackson
1.00013
Jefferson
1.00007
Karnes
1.00013
Kendall
1.00013
Kerr
1.00013
Kinney
1.00013
La Salle
1
Lavaca
1.00013
Live Oak
1
Matagorda
1.00013
Maverick
1.00007
McMullen
1
Medina
1.00013
Presidio
1.00002
County
Real
Refugio
Terrell
Uvalde
Val Verde
Victoria
Waller
Wharton
Wilson
Zavala
Surface Adjustment Factor
1.00013
1
1.00013
1.00013
1.00013
1.00013
1.00013
1.00013
1.00013
1.00013
Vince Hamilton
Zone 4205 South Zone
County
Surface Adjustment Factor
Brooks
1.00004
Cameron
0.99996
Duval
1.00004
Hidalgo
1.00004
Jim Hogg
1.00004
Jim Wells
1.00004
Kenedy
1.00004
Kleberg
1.00004
Nueces
1.00004
San Patricio
0.99996
Starr
1.00004
Webb
1.00003
Willacy
1.00004
Zapata
1.00004
Vince Hamilton
Scale Factors can be refined down
to the minute of Latitude
The next few pages have the scale factors
for the Texas South Central Zone for each
change of minute of Latitude.
Vince Hamilton
Surface Scale Factors
For Texas South Central
Zone 4204
Vince Hamilton
Surface Scale Factors
For Texas South Central
Zone 4204
Vince Hamilton
Surface Scale Factors
For Texas South Central
Zone 4204
Vince Hamilton
Surface Scale Factors
For Texas South Central
Zone 4204
Vince Hamilton
Surface Scale Factors
For Texas South Central
Zone 4204
Vince Hamilton
Surface Scale Factors
For Texas South Central
Zone 4204
Vince Hamilton
Units of measure (Linear)
Rectangular coordinate systems may use meters, international foot, or the U.S. Survey Foot as
the unit of measurement. (Most surveying and mapping work at the local level is based on the
U.S. Survey Foot.) When a conversion from one of these units to the other is performed, it is
important to ascertain which standard foot (U.S. Survey or international) is involved.
.
The international (S.I.) foot, based upon a redefinition of the meter in 1959,
is equivalent to 0.3048 meter.
The U.S. Survey Foot, upon which many years of land tenure information and legislation are
based, retained the 1893 definition of 1200/3937 meter*.
* For conversion of meters to U.S. Survey Foot, multiply the meters by 3.28083333333 (to 12
significant figures).
For conversion of meters to international feet, multiply the meters by 3.28083989501 (to 12
significant figures).
Vince Hamilton
What definition of a foot should we
be using?
Although the international foot is the latest
definition (1959), survey feet is still the
predominate unit because of the
implications with legacy surveys and deed
descriptions.
Vince Hamilton
Does it really matter?
• Short distances < 1000 feet
– US Survey Foot = International Foot (measured 1/100
of a foot)
• At 100,000 feet
– Definitions result in a difference of about .2 feet
• At 1,000,000 feet
– Definitions result in a difference of about 2 feet
• At 10,000,000 feet
– Definitions result in a difference of about 20 feet
Vince Hamilton
Edit the units.def file in Microstation
Comment out the ft definition using the # in the International Foot
And remove the # from the sf,ft definition in the US Survey Foot section.
Vince Hamilton
Using aerials in Microstation
In most cases the latest aerial photography
is created for planning and GIS use. The
images are typically in GRID coordinate
systems and in many cases in a different
mapping projection. The aerials are
normally clipped by a defined grid such as
the Lambert grid in this case. This is used
ti identify what aerials you need for your
project.
Vince Hamilton
Step by Step
•
•
In Microstation, add the aerial using the
coincident world option. The image should
have a world file that puts it in the right
location.
Check the coordinates to make sure it is in the
correct projection, it will not match up exactly
at this time so don’t worry. If the coordinates
are off by over a million you have a difference
in datums and will need to project a CAD
version of the grid to the correct datum and
use the interactive method to attach the aerials
using the grid corners.
Vince Hamilton
Native aerials in Microstation
Vince Hamilton
Save As HMR
3. In this case the aerials are in Mr. SID
format and they are cumbersome to use.
Export the aerials to .HMR for faster
display times.
Vince Hamilton
Attach as reference to project
5. After the aerials have been attached and
converted to HMR, exit the aerial file and
open the roadway in Microstation.
6. Attach the aerial file as a reference file.
Vince Hamilton
Before Scaling Reference File
Vince Hamilton
Apply the surface to grid scale
factor by scaling the reference file
Vince Hamilton
After Scaling the reference file
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One file, many references
One distinct advantage to this method is that
the aerial DGN file can be referenced to
different projects that might be using a
different scale factor. Because the aerials
are in their native position, you just need
to attach it as a reference and use the
correct scale factor.
Vince Hamilton
Magnetic Declination (NOAA)
http://www.ngdc.noaa.gov/seg/geomag/jsp/struts/calcIGRFWMM
Vince Hamilton
Vince Hamilton
Questions?
Vince Hamilton
[email protected]
281-539-7301