Land and Infrastructure SWG
Gruler, Hans-Christoph (Leica Geosystems AG)
1. Land Development SWG
The Land Development DWG was established by OGC (12-079r1) with the following proposed activities:
- Reviewing the current LandXML 1.2 schema and determining how best to continue to support the existing users and engage with them.
- Assessing the current industry support for the LandXML schema and whether multiple, incompatible versions of the schema have evolved.
- Investigating how to best incorporate LandXML into the OGC standards framework, including identifying places where there may be common elements in existing standards such as CityGML.
- Investigating the possibility of moving the LandXML schema into LandGML.
- Other efforts to integrate land information contained in various CAD formats into the OGC standards framework.
1.1 Conceptual Model
One of the initial problems to solve is gaining a better understanding of exactly what LandXML is and does. It exists only as an XML schema with minimal documentation throughout the code. There is no underlying conceptual model to explain the basic concepts that have been implemented with XML. It is difficult to gain a comprehensive understanding of LandXML by merely reading the extensive XML schema.
Most all OGC standards are based on underlying conceptual models. These may either exist as Abstract Specifications or as part of the standards themselves. For example, the OGC GML standard (among many others) implements the geometry concepts found in Abstract Specification Topic 1: Feature Geometry. It is not necessary (or even possible) to wade through GML’s XML schema to understand its geometric concepts.
So the first step in understanding what we have to work with with LandXML 1.2 would be to create a conceptual model. This would serve several purposes:
- Aid in the understanding of what LandXML 1.2 is and does
- Provide the basis for a conceptual model of what a future Land standard should do, based on an assessment of user requirements
- Establish a single set of consistent concepts that can be implemented in any set of implementation-specific standards, such a LandXML 2.0, a LandGML, a LandSQL, etc.
Because the OGC standard for modeling concepts is the Unified Modeling Language (UML), it is proposed that the Land concept model developed by this SWG be documented using UML.
buildingSMART has also expressed interest in developing a land standard based on LandXML as part of their openINFRA project. Their proposal is to develop a conceptual model as well, but using a modeling language consistent with other buildingSMART efforts, but different than UML.
OGC and buildingSMART will most likely have differing views on what might be appropriate in new Land standards because of their GIS- vs. building-orientation. However, it would be prudent for their resultant standards to be at least compatible. This can more easily be achieved if each is developed based on a conceptual model.
Developing two individual conceptual models, using different modeling languages would not necessarily be a bad thing. Each organization is more comfortable with their respective modeling languages and would therefore gain a better understanding of LandXML concepts when seeing them in their native language. It will be easier to ensure harmonization between the two models than it will be between resultant implementation standards, which is one reason for developing conceptual models in the first place.
2. Purpose of this Standards Working Group
The purpose of the Land Development SWG is to develop Land standards.
The SWG will ensure that all standards are consistent with the OGC standards baseline and business plan.
This SWG is a persistent SWG to enable it to work on:
1) a conceptual model for land development,
2) subsequent potential land information and development implementation-specific standards proposed by the Land Development DWG.
3. Business Value Proposition
The following business value proposition is taken from the Land Development DWG charter:
The LandXML community consists of over 650 organizations with 750 members in over 40 countries. There are over 70 registered software products that supported LandXML as of 2009.
A need exists for an organization like the OGC to assume the management of the LandXML schema and leverage the work that has been done over almost 10 years in developing the user community. This community is currently unsupported and not able to make complete use of the potential benefits that can come from active support of the schema and integration with other related OGC standards.
By the OGC adopting the LandXML schema, the user community will be assured of a formal process for maintaining, improving, documenting and in fact, formalizing the standard. This will lead to greater use of the standard and new opportunities for integration with other related OGC standards.
There will likely be other opportunities where CAD-based land information can be incorporated into the OGC standards framework as the process proceeds.
In order to gain a better understanding of LandXML 1.2 and to plan for its potential future within OGC, the first logical steps would be to:
1) identify user requirements
2) document the concepts that are supported by the LandXML XML schema
3) determine if the concepts support the requirements, and modify them accordingly
The first step more appropriately falls under the responsibility of the Land Development DWG. The second two will be the responsibility of this Land Development SWG.
4. Scope of Work
The scope of work of this Land Development SWG shall include the following activities:
1) Develop a conceptual model from the as-is LandXML 1.2 XML schema using UML class diagrams.
2) Develop a proposed conceptual model by modifying the as-is model, based on user requirement input from the Land Development DWG and other relevant sources.
3) Create an implementation-independent OGC Land Standard, Part 1 – Common Architecture based on the modified conceptual model.
Future work of the SWG shall be to develop implementation-specific Parts of the OGC Land Standard. These might include LandXML 2.0, LandGML, or others as the Land Improvement DWG may indicate or as the need may arise.
The Land Development SWG shall work closely with buildingSMART to either develop joint Land standards if appropriate or else to at least insure harmony between separate standards developed by each organization.
4.1 What is Out of Scope?
Unless directed otherwise by the Land Development DWG, this Land Development SWG should focus on the basic functionality covered in LandXML 1.2. This is not to exclude newer methods used to achieve similar results, such as true 3D roadway design.
4.2 Specific Contribution of Existing Work as a Starting Point
LandXML 1.2 shall be the starting point for this effort.
4.3 Determination of SWG Completion
The Land Development SWG will continue the work necessary to develop each candidate Land-based standard until it has been approved by the OGC Technical and Planning Committees as Adopted OGC standards.
As a persistent SWG, the voting members will have to vote to dissolve the SWG.
5. Description of Deliverables
The specific deliverables of this Land Development SWG shall include:
1) A conceptual model from the as-is LandXML 1.2 XML schema using UML class diagrams:
a) Where obvious errors are discovered, the UML should reflect the necessary corrections but such discrepancies shall be so documented.
b) An attempt shall be made to partition the schema content into logical UML packages, including documentation of package dependencies.
c) Other than a) and b) above, the model should reflect the as-is XML schema.
d) Relevant terms and definitions should also be documented in accordance with OGC convention.
e) Opportunities for improvement discovered during this process shall also be documented.
2) A proposed conceptual model developed by modifying the as-is model, based on user requirement input from the Land Development DWG and other relevant sources.
3) An implementation-independent OGC Land Standard, Part 1 – Common Architecture based on the modified conceptual model.
4) Additional, implementation-specific Parts of the OGC Land Standard. These might include LandXML 2.0, LandGML, or others as the Land Improvement DWG may indicate or as the need may arise.
The timetable for this work will vary greatly dependent upon the number of candidate standards proposed, actions of the Land Development DWG, and the cooperative efforts with buildingSMART. However, the first task listed is an immediate, crucial effort which shall commence immediately. This will help the Land Development DWG better understand LandXML and will therefore assist them in fulfilling their mission:
The mission of the Land Development DWG is to determine the best approach for the OGC to become the standards organization responsible for the LandXML data schema. Our role is to explore the potential options and determine the most appropriate method for supporting LandXML data types within the OGC data standards framework, as well as other land information that is currently not integrated with this framework.
6. IPR Policy for this SWG
R RAND-Royalty Free. RAND for fee
7. Anticipated Participants
Those involved in the planning, design, construction, operation and maintenance of Land-based infrastructure improvements including, but not limited to site development, utilities, roadways and similar facilities for other modes of transportation, and other land improvements such as irrigation systems, landscaping and drainage systems and structures.
This is not meant as a limiting statement but instead is intended to provide guidance to interested potential participants as to whether they wish to participate in this SWG.
8. Other Informative Remarks about this SWG
a. Similar or Applicable Standards Work (OGC and Elsewhere).
The following standards and projects may be relevant to the SWG's planned work:
OGC Abstract Specification Topic 1: Feature Geometry (ISO 19107)
OGC GML (3.2.1 and 3.3)
The SWG intends to seek and if possible maintain liaison with each of the organizations maintaining the above works.
b. Details of the First Meeting
The first meeting of the SWG will be held by telephone conference call as soon as the SWG charter has been accepted. Call-in information will be provided to the SWG's e-mail list and on the portal calendar in advance of the meeting.
c. Projected On-going Meeting Schedule
The work of the SWG will be carried out primarily by email and conference calls, possibly every two weeks, with face-to-face meetings perhaps at each of the OGC TC meetings.
d. Supporters of the Proposal
The following people support this proposal and are committed to the Charter and projected meeting schedule. These members are known as SWG Founding or Charter members. Once the SWG is officially activated, this group is immediately “opted-into” the SWG and have voting rights from the first day the SWG is officially formed. Extend the table as necessary.
Bentley Systems, Inc.
Gene V. Roe
Australian Department of Resources, Energy and Tourism
Dr. Paul Scarponcini shall act as convenor of this Land Development SWG.
Acknowledgements. Thanks to OASIS for providing a template as the basis for defining the OGC SWG template.