Source: http://hdfeos.org/workshops/ws04/presentations/Suresh/Suresh.ppt

1. HDF-EOS Vector
Data
Eugene Chi, Liping Di, R.Suresh
NASA/RITSS
Email: suresh@rattler.gsfc.nasa.gov
1

2. INTRODUCTION
HDF EOS library was primarily designed to support
raster data from Terra and other follow on projects
An increasing need to use Terra data with GIS
applications for regional and local use
Integration of Terra data with vector data will create new
applications and usage
Many GIS users will be able to access and use Terra data
2

3. HDF EOS Library
HDF-EOS Swath
HDF-EOS GRID
HDF-EOS Point
3

4. Vector Data Requirements
Need to support additional data types
GIS Users require vector data support
ESIP user community requested vector data support
Many ESIP investigators use vector data with Terra data
Advantages:
Terra data will be available to a new community of GIS users
Increase in Terra data use for many new applications
Vector data support will increase data inter use
Enhances data interoperability
Support for OGC WMT implementation
4

5. A Vector Data Set
5

6. A Vector Structure
Point Geometry and Attribute
PX
1.0
10.0
15.0
3.0
PX
1.0
1.0
15.0
10.0
Building Number Building Name
1
Physics
2
Earth Science
3
Mathematics
4
Chemistry
6

7. A Vector Structure (cont)
Line Geometry and Attribute
Line ID PX PY
1
1.0 1.0
1
10.0 1.0
1
15.0 15.0
2
15.0 15.0
2
3.0 10.0
3
3.0 10.0
3
1.0 1.0
Street Name
Campus Drive
Stadium Drive
Valley Road
7

8. A Vector Structure (cont)
Polygon Geometry and
Attribute
Polygon ID Line ID
1
1
2
1
3
Contiguity
1
Line ID Left Poly Right Poly
1
1
-1
Section
2
1
-1
Main Campus
3
1
-1
8

9. Components of the
Vector Interface
Access
Definition
Basic I/O
Inquiry
Subset
9

10. The Vector Interface
Routine Name
Category
Access
C
FORTRAN
Description
VCopen
VCcreate
Vcopen
Vccreate
VCattach
VCdetach
VCclose
Vcattach
Vcdetach
Vcclose
Definition
VCdefpoint
VCdefline
VCdefpoly
Vcdfpt
Vcdfline
Vcdfpoly
Creates a new file or opens an existing one
Creates a new vector data set and returns a
handle
Attaches to an existing vector data set
Releases a vector data set and frees memory
Closes the HDF-EOS file and deactivates the
vector interface
Define point attribute fields of a vector
Define line attribute fields of a vector
Define polygon attribute fields of a vector
Basic I/O
VCwritepoint
VCreadpoint
VCupdatepoint
VCwriteline
VCreadline
VCupdateline
VCwritepoly
VCreadpoly
Vcwrpt
Vcrdpt
Vcuppt
Vcwrline
Vcrdline
Vcupline
Vcwrpoly
Vcrdpoly
Writes (appends) new point records to a vector
Reads point records from a vector
Updates the specified point records of vector
Writes (appends) new line records to vector
Reads line records from a vector
Updates the specified line records of vector
Writes (appends) new polygon records to a vector
Reads polygon records from a vector
10

11. The Vector Interface
(cont)
VCupdatepoly
VCwriteattr
Subset
VCreadattr
VCnpoints
VCnlines
VCnpolys
vcrdattr
vcnpts
vcnlines
vcnpolys
VCpointinfo
VClineinfo
VCpolyinfo
VCattrinfo
VCinqattrs
Inquiry
vcuppoly
vcwrattr
vcptnfo
vclninfo
vcplinfo
vcattrinfo
vcinqattrs
VCinqvector
VCdefboxregion
VCregioninfo
VCregionrecs
vcinqvc
vcdefboxreg
vcreginfo
vcregrecs
Vcextractregion
vcextreg
Updates the specified polygon records of a vector
Creates or updates an attribute of the vector data
set
Reads existing attribute of vector data set
Returns the number of points in a vector data set
Returns the number of lines in a vector data set
Returns number of polygons defined in a vector
data set
Returns information about a given point
Returns information about a given line
Returns information about a given polygon
Returns information about a vector attribute
Retrieves number and names of attributes
defined for the vector data set
Retrieves number and names of vectors in file
Define region of interest by latitude and longitude
Returns information about defined region
Returns # of points, lines, polygons and records
within the region
Read a region of interests from a set of fields
11

12. Vector Subsetting
Features
By Geolocation
–
–
–
–
VCdefboxregion
VCregioninfo
VCregionrecs
VCextractregion
12

13. Tips on Writing a Vector
Attribute fields
– The name, type, order, and number of the
attributes of point, line, and polygon are
defined by users when first using them in a
vector structure.
– Once defined, the attributes are fixed with
respect to the vector.
13

14. Compression Method for
Vectors
NONE
14