TGN Critique

There are flaws, omissions, and things not completed in the TGN software development specification. But these are getting worked out as more conversations develop. Things will really get worked out when developers start building TGN into their apps.

That’s a highlight of this year, actually. I no longer look for ONE software company to build TGN into their platform. Neither do I imagine getting funding to do that myself. The reason is clear: the outcome is wrong. The idea of TGN is to make it easier to see and understand, interpret and make sense of, and make use of, complex digital modeled environments. That must not be confined to any single app. TGN is something that will make all modeling apps better. And it’s also about sharing interpretive insights, though shareable TGN rigs, with people using different modeling apps and platforms. Insight should be portable, transferable from one modeling environment to another.

TGN is for everyone, in every app, every platform. It’s a ridiculous ambition. And it takes a certain kind of stupidity to attempt to make it happen. That’s me. I’m stupid enough and obsessed enough with the task to do it. I believe I can convince a set of software companies to give it a shot. In time it will happen. And it will grow.


TGN: a digital model INTERACTIONS format standard (Apple Book)

TGN: a digital model INTERACTIONS format standard (ePub)

TGN: a digital model INTERACTIONS format standard (iCloud)

The purpose of the proposed development is to make things clear through interpretive interaction rigs, TGN rigs, within modeled digital environments.

Improved mechanisms of interactive close study of digital models (including digital twins), through TGN rigs, make user engagement with complex data more effective, more interactive, more clarifying, more communicative and expressive, and more revealing of insight. TGN might even bring the fun back into serious technical work by elevating the level of interpretive engagement in digital media.


0 1 TGN: rigging for insight  (2:16)

02 TGN: what is TGN exactly?  (5:35)

03 TGN: demonstration  (3:40)

04 TGN: portability  (5:17)

05 TGN: industry value  (9:27)

The dev platform I mention in the videos is iTwins.js, but TGN can be developed on every platform where TGN is useful and desired. The TGN demo shows a building model composed of several models obtained from different engineering disciplines (structural, architectural, civil/site, electrical, etc.). TGN is intended to be developed on app platforms that support 3D modeling formats, and the fusion of many different models from different sources.


THE major weakness of the TGN demo is that it includes none, or almost none, of the extra or non-model graphics that the TGN specification proposes. Below, I list aspects of extra graphics that are NOT shown in the demo video but are detailed in the TGN spec.

2021 TGN rig demo
2012 hypermodel, Microstation, automated drawing-model fusion

TGN is an extension (and re-engineering and improvement) of my earlier work on the automatic presentation of complete CAD drawings at true orientation within models (2012 hypermodel example above). But the TGN demo video fails to show that. You can imagine it. But I’ll improve the demo soon. TGN includes that concept. I proposed hypermodel (more examples HERE) and led the team that designed, developed, and in 2012 first commercialized hypermodel. Now 10 years later, TGN is richer than hypermodel in terms of graphical expression, user interactivity, communicative impact, and cross platform portability. TGN represents a major increase in user engagement in the close study of complex models. And the TGN technical infrastructure makes the old hypermodel patents irrelevant and obsolete.

From the spec T3.2 TGN Viewing ArcTGN rigs have a built-in viewing arc, a path selected by the TGN author (or set by default), that allows a controlled viewing path for each TGN rig. Hypermodel does not have this feature. TGN users are not restricted to viewing ONLY along the TGN viewing arc. Viewing is allowed from ANY position in 3D space. But controlled viewing along the rig’s built in viewing path is also supported. Users are free to navigate along the path, or jump off the path at any time. The viewing arc enables a new feature related to CAD/ extra graphics, see next items.

Extra graphics are built into the TGN rigs. How do the graphics GET THERE? 

TGN supports three graphics authoring methods 

These are mutually non-exclusive optional methods. Different TGN implementations in different apps may support one or more of these options. Refer to TGN spec items: 

T3.4 transform TGN camera to parallel projection at viewing arc position p2 and 

T3.5 graphics generation (and drawing style) at TGN viewing arc position p2:

  1. The TGN author user uses CAD or CAD-like or illustration tools for text, lines, arcs, shapes, dimensions, etc. to author extra graphics into a TGN rig. The extra graphics, from the spec section T3.9 extra graphics, can be authored either
    1. at the p2 position of the TGN viewing arc (on a flat plane, just like in hypermodel), and/or, 
    2. the extra graphics may be authored anywhere in 3D, placed by the author anywhere along the TGN viewing arc. This way, extra graphics can be (from the spec) T3.11 progressive display along viewing arc, authored in a way that tells a clearer story. The idea is that the extra graphics can be presented progressively along the viewing arc, so that some things are revealed, highlighted, clarified, earlier in the viewing experience, and others are revealed later. This way a TGN rig tells a story, and takes advantage of the best capabilities of 3D graphics, to focus and clarify what matters in a way that is not confined to just a flat plane like conventional drawings. 
    3. HOWEVER, this is one of the elegant ideas of the TGN rig, all of those extra graphics become normalized to a plane at position p2 of the TGN view arc, and transformed into flat graphics at the (from the spec) T2.1 TGN p2 I/O to CAD formats.
  2. But in some workflows, the user who creates the TGN rigs in models does not want to use the TGN extra graphics tools described above (or, those graphics tools are not available in their app). For those users, the T2.1 TGN p2 I/O to CAD formats will support import and export of TGN graphics at position p2 (or optionally from any position) to and from common CAD formats, or optionally, other non-CAD graphics formats.
    1. T2.1 TGN p2 I/O to CAD formats means that the extra graphics that are presented at position p2 (center of viewing arc) of any TGN rig can be authored by users who prefer ANY graphics app or format (e.g., AutoCAD, DWG)
    2. T2.1 TGN p2 I/O to CAD formats is complemented with an optional  T2.2 Flat Arrays of p2 TGN graphics. This combination will provide a powerful and very flexible optional method, and probably much used method, for getting extra graphics into, and out of, TGNs. Use of T2.1 in fact will be a very elegant and powerful way for CAD users to easily upgrade and elevate the communicative power of their drawings, because they will be presented in-situ within TGN rigs, within models. Please see the spec for detailed discussion.
  3. The third way for getting extra graphics into TGNs is in the T1 section of the spec: 
    1. T1.1 TGN UPGRADE of Legacy Drawings produced by conventional BIM (Building Information Model) Apps
    2. T1.2 TGN UPGRADE of Legacy Drawings in ANY FORM from ANY SOURCE

Read the rest of the TGN spec. Extra graphics function in combination with other TGN features.

Developer Note

I can help design your TGN implementation. I’m one message away. Message me: \rob snyder Linkedin

I can help: 

  • design your implementation of drawing-model fusion (hypermodel)  
  • get that module ready for upgrade to TGN
    – or leapfrog ahead and –
  • design your implementation of TGN
  • plan for TGN interoperability across platforms and apps and the huge diversity of modeling formats

[Tangerine] Makes Insight Tangible

Spatial Media Innovation and Cognitive Computing

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