Overview
GTViewer has
supported a feature call Style Name Maps
since version 9 (circa August 2010).
This feature is a fairly significant addition to GTViewer, but it has not
been promoted much since it was introduced.
With the Style Name Maps, the
GTViewer element format was upgraded to include a 32 bit integer value to store
a Style Definition Id. If a Style
Definition Id is not provided for an element, the element format will
appear unchanged and is still compatible with versions of GTViewer prior to
version 9. However, with this new
feature you can define a Style
Definition Id on an element which is mapped to a Style Definition for a given Zoom Level range via the Style Name Map. Thus, the element’s Style Definition no longer must be bound to its Filter Id. This subtle change turns out to be a major
shift in the way GTViewer data can be created.
The Style Name Map
feature has been largely ignored over the last few years for several
reasons. First, changing the element
format is a fairly major change to GTViewer. Since the element format support has been available
for a while now, adding Style Definition
Ids to your data will not cause problems with older versions of GTViewer
(but the new functionality won’t be supported either). Second, support for the Style Name Map was not available in a .GTX extract file. Third, it has taken a while for the GTData tools and the FME Writer Plugin
to catch up, and there has not been a good way to create data using the Style Definition Id without manually
generating your data with the GTData
Objects.
With Version 14 of GTViewer, all of these problems have been
addressed. The Style Name Maps are now fully supported in both the GTM and GTX
files. Style Name Maps have also been enhanced to map Style Names directly to Style
Definitions or to an Abstract Name
which is then mapped to a set of zoom level threshold ranges mapped to a style
definition. GTData tools such as GTIndex,
GTPack, and GTExtract have been updated to support Style Name Maps, and the FME
Writer Plugin has also been enhanced to not only support the Style Definition Id, but to also
provide a new mode for generating Filter
Files that are decoupled from the Style Definition File (something not
possible with previous versions of the plugin).
The Style Name Map
The Style Name Map
is a text file that defines how a Style
Definition Id (defined on the GTViewer element) is mapped to a Style Definition defined in the Style Definition File (usually called
style.def). The Style
Definition contains a set of properties (color, weight, linestyle, size,
justification, etc.) that define how an
element appears when it is rendered in GTViewer and has traditionally been used
with the Style Map File (usually
called Style.map). The Style Map File maps a Category and Filter Id to a Style
Definition Name; whereas, the Style
Name Map File maps the Style
Definition Id on the individual element to a Style Definition Name.
The Style Name Map File
contains two sections. The first
section, called Id To Name, maps a Style Definition Id number to an Abstract Style Name. This section’s entries are in the following
format:
[Style Definition Id] = [Abstract
Style Name]
Both the Style
Definition Id and Abstract Style Name must be unique for all
entries.
The second section, called Name to Style, is optional.
If it is not defined in the Name
to Style section, an Abstract Style Name
will be mapped to a Style Definition
of the same name. However, you can map
an Abstract Style Name to one or
more entries of the following format:
[Abstract
Style Name] = [Style Definition Name]
or
[Abstract
Style Name] = [Style Definition Name]|[min threshold]|[max
threshold]
Here, the Abstract Style Name is mapped to a Style Definition Name. If the min and max threshold values are not provided, they will default to 0 (not used).
The following example shows a Style Name Map:
StyleNameMap.map
1=STREETS - A21
2=STREETS - A51
3=STREETS - A63
4=STREETS - A31
5=STREETS - A15
6=STREETS - A35
7=STREETS - A25
[Name To Style]
STREETS - A15=Main Road - CLose|0|100
STREETS - A15=Main Road - Far|100|0
STREETS - A21=Main Road - CLose|0|100
STREETS - A21=Main Road - Far|100|0
Here the Id to Name section maps Style
Definition Ids 1 to 7 to Abstract Style Names.
In this example, the ids are mapped to different classifications of road
types (A21, A51, etc.). Here only,
Streets – A15 and Streets – A21 are defined in the Name to Style section because they are the only ones that have
different style definitions used for different Zoom Level Ranges. The rest of the Abstract Style Names just
default to a Style Definition of the same name.
The Style Definition File
(style.def) for this Style Name Map
would look like this:
Style.Def
[STREETS - A21]
ColorValue=100|100|100
[STREETS - A51]
ColorValue=100|100|100
[STREETS - A63]
ColorValue=100|100|100
[STREETS - A31]
ColorValue=100|100|100
[STREETS - A15]
ColorValue=100|100|100
[STREETS - A35]
ColorValue=100|100|100
[STREETS - A25]
ColorValue=100|100|100
[Main Road - Close]
ColorValue=255|0|0
Weight=5
[Main Road - Far]
ColorValue=0|0|255
Weight=3
Style=2
All of the
lesser roads are just styled as gray lines while the Major Roads (A21 and A15)
are styled as dashed blue lines when zoomed out far and solid red lines when
zoomed in close. The following
screenshots show the difference.
Far Out:
Close In:
The Category
definition for the Roads in the GTM file looks like the following:
Name=Category 2
IndexFile=test_2.gtn
graphicsFile=test_2.gtg
Filter=test_2.flt
StyleNameMap=StyleNameMap.map
DisplayStatus=0
MinDisplayThreshold=0
MaxDisplayThreshold=0
SelectFlag=0
DataId=1
The General
Info section would still contain the entries to define the Style Definition
File and the Style Map File (no different than before):
StyleMapFile=Style.map
The Style Map File just contains a header
entry to make it a valid file (no mappings are provided):
Style.Map
# FilterMap|min|max|category|filterIdLow|filterIdHigh|Style|
One question
that you may have is: Why are the
Style.def and Style.map files defined in the General Info section while the
Style Name Map is defined in the Category section? This is because each Category can have its
own Style Name Map, or they can
share a Style Name Map with other
categories. If more than one Category
section specifies the same Style Name
Map File, they will share it. All
of the Style Name Maps will use the
Style Definitions in the Style
Definition File.
Attribute
Info Dialog
The Style Name
Map and Style Definition Id are
both displayed in the Attribute Info
Dialog on the Element tab:
Major Road -
Far Out
Major Road - Close In
Style Map versus Style Name Map
The Style Map and Style Definitions have been supported by GTViewer since version 1.1.
They are used by all current conversion tools including those for G/Technology,
Smallworld, Oracle Spatial, and Millsoft.
The FME Writer Plugin also uses them extensively.
The Style Map is a very powerful tool for
assigning symbology to elements. By
mapping the Filter Id to a Style Definition, it allows you to
defer specifying the actual Style
Definition properties until after the data is converted, and you can change
styles without reconverting the data.
Before the Style Map was
supported, each element had to have its style explicitly defined at conversion,
and the style could not be changed without changing the element (or
reconverting the data). While this
method sounds primitive, it does work quiet well for Microstation and AutoCad
data or any data whose styles are Instance
Based and cannot be easily generalized.
The Style Map also has to
ability to map Filter Ids to a Style Definition based on a Zoom Level Range, so you can specify
different symbology for the same element at different zoom levels (also
something that Instance Based symbology can’t do).
The Filter Id, which is required on all GTViewer elements, is used to control
the display of elements in the view. The
Filter Files map the Filter Id to a user-friendly name and
also groups them together into logical sets of features. When the user uses the Display Filter Dialog in GTViewer,
it basically tells which Filter Ids
can be display and which ones will be hidden, then when the view is rendered
only elements with the displayed Filter
Ids will be drawn. One drawback to using
the Filter Id for both display
control and style mapping is that the display filter resolution must match the
same resolution required to allow all of the required styles. For example, let say you have a Primary
Conductor, and you want to have two display groups (Overhead and
Underground). However, your symbology needs
to show both orientation and number of phases:
o
Above Ground – 1 Phase
o
Above Ground – 2 Phase
o
Above Ground – 3 Phase
o
Underground – 1 Phase
o
Underground – 2 Phase
o
Underground – 3 Phase
We will need
6 Filter Ids to support all 6 styles.
You can do some creative grouping to make simplify the Display Filters
to 2 groups (Above Ground and Underground), and you may actually want to be
able to control the display at this resolution. But this problem can grow out of hand pretty
quickly. What if we wanted to add state
to the symbology? If we just used
Proposed, Inservice, and Retired, you would need 18 Filter Ids to support all
of the different styles.
As mentioned
early, the Style Name Map unbinds
the Filter Id from the Style Definition. So, the Style
Definition Id has no dependence on the Filter
Id, and your Display Filters can
be whatever you want, while your Style
Definition Id can specify the styles you need. The Style
Definiton Id is an Instance Based property, but it still has the advantage
of deferring the specification of the Style Properties until after the data
conversion and allowing changes to the Styles without reconverting the
data. The cost here is that the GTViewer
elements are slightly larger (4 bytes).
You can also
use Style Maps and Style Name Maps at the same time. The Style
Map will always take precedence, and it may become unnecessarily complex if
you use both methods for defining styles at the same time. Not a
recommended approach, but fully supported.
Creating Data with Style Name Maps
Currently,
the easiest way to create GTViewer
data that uses a Style Name Map and Style Definition Ids is to use the GTViewer FME Writer Plugin. For those of you who have used the GTViewer
FME Writer Plugin before, there are a few things that are different. There are some new Filter File creation modes and several new Format attributes. If you have existing FME Workbenches, it will
be difficult (but not impossible) to migrate them to the new modes; however, it
is recommended to just create a new workbench and use the new modes.
I will
illustrate using the new modes with a simple example. I will convert the TIGER data seen in the
examples above and go through each step of the process.
(tgr01089lkA.shp which contains roads).
The Writer will be GTI_GTViewer and I
will give it Demo.gtm as the dataset to create.
The TIGER
data is in an LL-83 projection (Latitude/Longitude), so the Coordinate Factors are for this are the
standard values for latitude/longitude data (200/1000000/0). The Filter
Creation Mode is set to styleNameMap_global
which will create one Style Name Map
for the entire conversion. You could
select styleNameMap_byCat to create
a separate Style Name Map for each
category. The default mode for
FilterCreateMode is Enhanced which creates the normal Style Map and Style
Definition files.
- gti_groupFilterName – specifies the Filter File Group for the feature created. If this entry is not specified, it will default to “Features”.
- gti_FilterName – specifies the name of the Filter Name for the feature created. All features using this Filter Name will have the same Filter Id. If this entry is not specified, it will default to the gti_featureName value ( which will default to the Reader’s Feature Type name if not defined).
- gti_style_def_id – specifies the Style Definition Id to put on the element. This entry should only be used if you are manually setting the Style Definition Id, which is generally not the case. It is similar to using the gti_filterId attribute (which is also rarely used).
- gti_featureName – specifies the name of the feature. If this attribute is not defined, the Feature Type for the reader will be used as the default.
- gti_categoryId
- gti_filterGroupName
- gti_filterName
- gti_styleName
- gti_featureName
- Set gti_categoryId to 2 (even though this is the default).
- Set gti_styleName to the CFCC attribute. This is the Census Feature Class Code and is a good attribute for specifying different styles for the roads. A15 is an Interstate, A21 is a Primary road. These road types will be styled differently than the others.
1=TGR01089LKA - A41
2=TGR01089LKA - A21
3=TGR01089LKA - A51
4=TGR01089LKA - A63
5=TGR01089LKA - A31
6=TGR01089LKA - A15
7=TGR01089LKA - A35
8=TGR01089LKA - A25
9=TGR01089LKA - A71
10=TGR01089LKA - A74
11=TGR01089LKA - A11
12=TGR01089LKA - P41
[Name To Style]
An Abstract Style Name is created for each CFCC value found in the
data. Since the Use Feature Name in Style Name option is set to Yes, the Feature Type Name is prepended to the
value (in this example it is TGR001089LKA).
If we had set the gti_filterGroupName
or gti_featureName to a value like
“Roads” then the Style Name Map would look like:
1=Roads - A41
2=Roads - A21
3=Roads - A51
4=Roads - A63
5=Roads - A31
6=Roads - A15
7=Roads - A35
8=Roads - A25
9=Roads - A71
10=Roads - A74
11=Roads - A11
12=Roads - P41
[Name To Style]
The Filter File created by this
conversion would look like this:
[Filter
Info]1|1|0|0|100|FEATURES|GROUP:FEATURES,1|0|0|0|0|
2|1|1|1|100|ROADS|GIS1:1,1,FEATURES,ROADS|0|0|0|0|
If gti_filterGroupName is set to “Roads” this will change the group
name to “Roads” like this:
1|1|0|0|100|ROADS|GROUP:ROADS,1|0|0|0|0|
2|1|1|1|100|ROADS|GIS1:1,1,ROADS,ROADS|0|0|0|0|
In this case, setting the group name
may not be very useful since the Group and the Filter Item are the same name.
If gti_featureName (instead of gti_filterGroupName) is set to “Roads”
this will change the feature name to “Roads”, but not the group name like this:
1|1|0|0|100|FEATURES|GROUP:FEATURES,1|0|0|0|0|
2|1|1|1|100|ROADS|GIS1:1,1,FEATURES,ROADS|0|0|0|0|
The
Attribute Value Mapper Transformer just set the A15 and A21 value to “Major
Road” and the default is “Minor Road”
The Style
Name Map is simplified to the following with this change:
1=ROADS - MINOR ROAD
2=ROADS - MAJOR ROAD
[Name To Style]
Since the gti_filterName is not set, the filter
name will default to the feature name:
1|1|0|0|100|FEATURES|GROUP:FEATURES,1|0|0|0|0|
2|1|1|1|100|ROADS|GIS1:1,1,FEATURES,ROADS|0|0|0|0|
However, if
we also set the gti_filterName
format attribute to the Road_Type value produced by the Value Mapper
transformer, we can have Minor Roads and Major roads as the two Filter File
entries:
The Filter File
will look like the following:
1|1|0|0|100|FEATURES|GROUP:FEATURES,1|0|0|0|0|
2|1|1|1|100|MINOR ROAD|GIS1:1,1,FEATURES,MINOR ROAD|0|0|0|0|
3|1|2|1|100|MAJOR ROAD|GIS1:1,2,FEATURES,MAJOR ROAD|0|0|0|0|
The only
change here from the previous example is that the gti_styleName is set to CFCC instead of the Road_Type attribute. The gti_filterName
is still set to Road_Type. The Style Name Map looks like this:
1=ROADS - A41
2=ROADS - A21
3=ROADS - A51
4=ROADS - A63
5=ROADS - A31
6=ROADS - A15
7=ROADS - A35
8=ROADS - A25
9=ROADS - A71
10=ROADS - A74
11=ROADS - A11
12=ROADS - P41
[Name To Style]
And the Filter File looks like this:
1|1|0|0|100|FEATURES|GROUP:FEATURES,1|0|0|0|0|
2|1|1|1|100|MINOR ROAD|GIS1:1,1,FEATURES,MINOR ROAD|0|0|0|0|
3|1|2|1|100|MAJOR ROAD|GIS1:1,2,FEATURES,MAJOR ROAD|0|0|0|0|
Now, we have
12 different Style Definitions used
with only two Filter Ids. This could not be done with the old Style
Map. And while this change is subtle, it
does provide a powerful new way to organize your data. If you had wanted to keep all 12 Style
Definitoin for the individual road type, the Filter Display would have looked
like this with the Enhanced mode:
Whereas it
looks like this with the Style Name Map while
still having all 12 styles:
The Style Name Map and Style Definition Id are new tools for you to use. There is no reason to switch to this method
of creating data unless you have a particular reason to. However, if you are just starting to convert
your data to the GTViewer format, it is an option that you should consider.
