Transcript Features

Features
Remcom Inc.
315 S. Allen St., Suite 416  State College, PA 16801  USA
Tel: 1-814-861-1299  Fax: 1-814-861-1308  [email protected]  www.remcom.com
© 2011 Remcom Inc. All rights reserved.
What are Features?
• Types: City, Terrain, Foliage, Indoor Floor Plan
and Object
• Hierarchical organization: Feature  Structure
group  Structure  Sub-structure  Face
• Geometrical data in vector format
• Electromagnetic material properties
• Display properties
• Geographic positioning and reference system
Hierarchical Organization of Features
Hierarchical layout of a structure
Feature
(City, Terrain, etc)
Structure group
Structure
Structure
Sub-structure
Face
Face
Face
Face
Feature
Structure Group
Structure
Sub-Structure
Face
Motivation for Hierarchy
• Having a multi-layered topology provides the
user with flexibility
• Tools will be added to allow more extensive
editing of the organization of these layers
Geometry File Formats
• All feature types use a very similar file format
described in the Appendix in the User’s Manual
• Usually, files only differ by extension and the
highest level “delimiter”
• File extensions:
–
–
–
–
–
.city for buildings
.ter for terrain
.veg for foliage
.flp for indoor floor plans
.obj for objects
Importing Building Data
• InSite’s physics-based propagation models require full
three-dimensional building data
• Accurate data for a large number of cities is now
available from a growing number of sources
• Data is often available in AutoCAD’s DXF format
• After importing, material properties can be quickly
assigned to each building with the GUI
• Buildings are automatically fit to the underlying terrain
• Imported building data can be in latitude/longitude, UTM,
or Cartesian coordinates
Fitting Buildings to Terrain
• Enabled when terrain is present in the project
• Options are to extrude the footprint of all substructures down to the terrain, or to lower the
entire sub-structure to the terrain. With
extrusion, the roofs of the sub-structures remain
constant.
• Building is either extruded or lowered to the
minimum terrain elevation below each substructure
Importing DXF Files
• Primarily used for importing city data
• Coordinate system used in the DXF file must be
known
• Whether the elevations in the file are relative to
sea level or terrain must be known
• Wall materials and roof material can be set
independently
Allowed DXF Data Types
• InSite is only capable of converting the following
DXF tags:
– Polylines
– Polyface meshes
– 3D faces
• Roofs should be placed on top of all buildings to
ensure calculations are performed correctly
• “Floor” faces on the bottom of the building are
not usually necessary, but can be retained if
they are present in the DXF file
Importing ESRI Shapefiles
• To import an ESRI shapefile
containing building footprint and
height information into the current
project, select
ProjectImportShapefile
• Only polygon and polygonZ shape
entities are supported
• Some shapefiles are accompanied
by a .prj file containing coordinate
projection information. The .prj file
projection information is not
currently supported and the
imported geometry may not be
correctly geo-referenced.
Raster Data Import
• Raster data files
contain grids of height
values
• Data usually measured
from aerial or satellite
photography or LIDAR
• Raster converter
extracts footprints from
the grids and creates
buildings from the
footprints
Raster Data Import (2)
• Raster Data Import window previews raster and
vector data
• Allows cropping, scaling and extrusion
• Supports PGM and ARC ASCII grid files
Building Preprocessor
• InSite’s building preprocessor puts data into a form ready for
calculation
• Building databases are usually obtained from high resolution
aerial photographs and will often include very small features
which can lead to long computation times and, in some cases,
less accurate results
• Remcom’s building simplification algorithms are based on
removing small building faces, combining nearby coplanar
faces, and removing concave corners
• The change in the area and perimeter of the footprint is
monitored during modification to avoid changes which distort
the basic shape of the building
Building Simplification Interface
Building Preprocessor Example:
Before
Before
Building Preprocessor Example:
After
After
City Editor
• Draw footprints of
new buildings (substructures) and
then set height
• Edit and delete
existing buildings
• “Snap-to” grid lines
and vertex options
are available
• Active images will
appear in the editor
window
Origin of Cartesian Reference Frame
• Wireless InSite supports data in:
– Cartesian form relative to an origin at a given latitude/longitude
– Latitude/Longitude
– UTM using various ellipsoids
• Points close to the origin are transformed with least error
• All feature origins do not have to use the same latitude
and longitude
• It is recommended that foliage items and terrains have
the same origin
• A feature’s default origin is determined from the first
point read in and is centered on imported terrains
The Global Origin
• Wireless InSite converts all projections to
Cartesian for display and for calculation
• A global origin is determined from all loaded
features, transmitters, receivers and study areas
– Usually the minimum of all geometrical elements
– Can be manually set in order to reduce error
Geographic Projections
• Everything positioned in a project has an origin
• Every origin has a latitude/longitude
• Cartesian data includes latitude/longitude of
origin
Transform to Cartesian Coordinates
• Coordinates given in UTM are first converted to
latitude/longitude
• Coordinates in latitude/longitude are converted
to Cartesian coordinates using:
X = REarth * cos(0) * ( - 0)
Y = REarth * ( - 0 )
Where  = Latitude
 = Longitude
0 = Global origin latitude
 0 = Global origin longitude in radians, and REarth is the
mean radius of the earth
Minimizing Projection Error
• By default, the global origin is set to minimum
latitude/longitude
– Unfortunately, this can introduce errors in relative
positions
• Averaging all latitude/longitude values to
determine the global origin produces less error
• Averaging the locations of all vertices will
produce the least amount of error
Materials
• Each feature maintains its own list of material definitions
for all items within it
• Predefined types are accessible in the Material database
• Identified by an integer value within each feature file
• Each face is assigned a material using this integer
• A face can be double-sided (mainly indoor)
– Material thickness is used to display depth in walls
– Same material will be assigned to both sides
• Material properties, with respect to the calculation, are
covered in another section
Material Type Legend
• A color coded legend
of all materials in a
project can display on
the right side of the
project view
• Clicking on an entry
in this table brings up
the material’s
properties, which can
be edited
Terrain
• A new terrain can be created either as a
rectangular region or as a profile
• The editor that is available is determined by which
type of terrain is being created/edited
Editing a terrain surface
Editing a terrain profile
Terrain Surface Editor
•
•
•
•
Points can be moved and added
Point elevation is changed by right clicking
Terrain can be created as a grid initially
Heights can automatically be set to either fit the
terrain or to lower the edges of buildings
• Useful for creating relatively simple terrains to
place below cities
Terrain Profile Editor
• Points can be added or removed from the profile
• Points can be moved within the profile as long
as it remains between the points to its side
• To modify the material on a face to the right of a
point, right-click on the point and select the
Modify option from the context menu
Importing Terrain
• Terrain can be
imported from USGS,
DTED, or DTA
(SoftWright) data files
– DTED levels 0, 1, 2
– USGS 7.5’, and 1º
DEMs
– 30” DTA
Importing Terrain (2)
• A region of any size can be imported. It is
recommended that users adjust the settings of the
importer to minimize the number of faces while retaining
the accuracy of the calculation.
• Local repositories of terrain data can be indexed to allow
Wireless InSite to locate the files it needs automatically
• A terrain can be imported as a profile or a rectangular
region
View of Terrain in Colorado Mountains
with Tx and Rx Locations
Foliage Data
• Foliage can be imported from the Global Land
Cover Characteristics (GLCC) database
available from the Land Processes Distributed
Active Archive Center (LDAAC) website
• New foliage can be created manually using the
Foliage editor
Foliage Editor
• Works in a manner very similar to the City editor
• New foliage areas can be added/deleted
• Points can be moved or deleted after a foliage
area has been created
• The height of individual foliage areas can be
adjusted
• Foliage areas can be conformed to the terrain
Foliage Editor (2)
Foliage Database
• Geo-referenced foliage information can be imported
using the Global Land Cover Characteristics (GLCC)
version 2 database
• Data is available through the Land Processes Distributed
Active Archive Center (LDAAC) website
• Includes foliage information in 1km2 resolution and is
available for 5 major geographical regions; Africa,
Australia Pacific, Eurasia, North America and South
America
• During the import process foliage areas can be
previewed. This enables the user to cut out
unnecessary/unwanted foliage areas and make
adjustments to the materials
Foliage Capabilities
• Foliage areas can be created and edited from the GUI
• The horizontal footprint is defined first using the GUI’s
drawing tools
• An upper and lower height can be assigned to each area
• Areas can be stacked vertically in order to distinguish
between the canopy and the undergrowth
• An effective permittivity and conductivity is assigned to
each area
• A roughness parameter can be assigned to each face
Foliage Capabilities (2)
• Transmitters and receivers can be inside or outside of
foliage areas
• No change in direction of rays through foliage is
calculated
• The distance propagated through each foliage area is
found for each ray path
• An exponential decay is applied to each E-field
• Phase change of E-field can be also included
• Lateral wave along canopy-air interface is also included
Foliage Capabilities (3)
• Foliage areas can be created and
edited from the GUI
• The horizontal footprint is defined
first using the GUI’s drawing tools
• An upper and lower height can be
assigned to each area
• Areas can be stacked vertically in
order to distinguish between the
canopy and the undergrowth
• An effective permittivity and
conductivity is assigned to each
area
Foliage Areas in an Urban Environment