u p F r o n t . e Z i n e
the business of cad
Issue #701 | July 26, 2011
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In This Issue
1. Spatial CGM Capabilities Webinar
2. Updating Civil B
Part 3: CivilB Replies to Autodesk's Response
3. Out of the Inbox and our other regular columns
Spatial CGM Capabilities Webinar
Spatial last week released its CGM API [Convergence Geometric Modeler application programming interface], first announced a year ago. This is a significant step for Dassault Systemes, until recently seen as a CAD vendor that was disinterested in being open with its data formats. Sure, there is the XVL-based 3DXML, but it was not well documented and only provided lightweight representations of CAD models created by Catia. The most significant on-going irritant was the inability of Dassault Systems to provide a way for little stepbrother SolidWorks to read models from Catia -- and vice versa. There are third-party translators, but those cost extra and in any case the perception was bad.
(Under V6, Catia and SolidWorks will interchange models, but the data is "locked" in an Enovia database, which does not store model data in the traditional sense, and so cannot be easily extracted by competitor CAD systems.)
Spatial is a division of Dassault Systems, and they were given the job of commercializing CGM, the solid and surface modeler used by Catia. Competitors can now license the official API for reading and writing Catia models and other data. Last week, Aptial held a Webinar in celebration of the release of their CGM API. I joined the 7:00 a.m. Webinar late, first sleeping in, then being prevented from joining by WebEx, which thought the Webinar would not start for another nine hours. I did record the entire Q&A, and here is my paraphrase of it.
Q: Will CGM compliment ACIS? Will they interoperate?
A: Both are still being developed; 3D InterOP allows them to interoperate data-wise, but they are not compatible. If you are not sure which one to adopt, Spatial staff will look at your needs and then recommend which one to use.
Q: Is there 1:1 mapping between the ACIS and CGM APIs?
A: No. CGM is completely object-oriented, while ACIS is partly object-oriented and partly procedura, because the two were developed differently.
Q: What platforms will CGM run on?
A: The current release R2012 runs on Windows 32- and 64-bit; the next release near the end of this year will add Linux 32- and 64-bit.
Q: Do I need RADF [Spatial's Rapid Application Development Framework; see http://doc.spatial.com/index.php/Portal:RADF] to develop with CGM?
A: No, you can also use C++.
Q: Does CGM have a bridge to HOOPS [see http://doc.spatial.com/index.php/HOOPS]?
A: This is in development now; we will provide it by the end of the year.
Q: Does CGM have a C# interface?
A: Yes; it has a complete C# wrapper for those wanting to develop in .Net, in contrast to ACIS.
Q: Is it possible to write Catia plug-in, like in CAA [component application architecture, which is Dassault's API for Catia]?
A: No, not 100%. It is not exactly the same, because of differences in parts management. You can reuse some pieces from CAA.
Q: Is there a separate read-write module in CGM format?
A: You can save data in CGM format.
Q: Can V6 data be read?
A: Yes, it can be read through the Cadpart product data format. Native V6 has no file format; all data is stored in the Enovia database.
Q: Does it support PMI [product and manufacturing information]?
A: Not today. We will add PMI in the next two releases, in November and in Q2 next year.
Q: Do you have different products with different functions at different costs?
A: There are two: (a) the full CGM modeler, and (b) CGM Exchange, which read-writes CGM data and includes the tesselation viewer.
Q: Is there an interface with 3DXML [Dassault's lightweight file format for sharing Catia data; see http://www.3ds.com/products/3dvia/3d-xml/overview]?
A: Not today, because 3DXML export format contains no precise 3D data.
Q: Will there be a scripting interface, like Scheme in ACIS?
A: We are developing it; it might be in Python. We recognize the value of the scripting interface for prototyping.
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Part 3: CivilB Replies to Autodesk Response
[Last week, Autodesk's Adam Strafaci responded to some of Bo Gao's statements regarding CivilB vs other software, in upFront.eZine #699. Through this series of exchanges, we trust that our readers better understand the issues first raised by Mr Gao..]
We spent many years developing the Civil Engineering Objects (CEO) model and our CivilB software. Because the CEO model is new, it's warranted to provide more detail. The intent of the CEO model is to address two essential issues in roadway and infrastructure reconstruction design:
- Avoid design interferences and utility conflicts among existing and proposed facilities.
- Model existing roadway and grading surfaces (as well as proposed widening, overlay, and modifications) in a way that is intuitive to civil engineers.
Avoiding Design Interferences
The issue is not so much about "hard" or "soft" clashes, but about how to model 3D geometry of civil engineering objects, and how to handle specialized civil engineering clearances. Navisworks (and most other 3D modeling software) comes from 3D parametric modeling, which uses 3D geometric objects (such as cubes, cones, and cylinders), surfaces, and meshes to define object outline geometry.
In civil engineering, the survey-design-construction-GIS data cycle, we use 3D points and 3D centerlines (known as "horizontal alignments" and "profile") to define the positions of objects, and then cross sections to define their outline geometry.
The CEO model use the same concept, defining 3D geometry of spot, linear, and surface (polygon) objects. Horizontal alignments and profiles of linear objects are related to many civil engineering design standards, while cones and cylinders are not. (See our brochure at www.civilb.com for more details.)
To return to the topic of soft and hard clashes. A soft clash is the minimum 3D distance between 3D surfaces of two objects; there are various ways to calculate the clearances. CivilB use CEO models to verify four clearances specific to civil engineering, as described by upFront.eZine. Figure 1 illustrates a typical problem.
Figure 1: Red pipe is too close to the blue foundation; green pipe meets civil engineering clearance requirements.
In the section view, the red water pipe does not conflict with the blue bridge foundation from a minimum 3D clearance standpoint; in civil engineering design, however, the top view shows that the pipe and the foundation must meet a minimum horizontal clearance to provide proper maintenance easements. The pipe must be relocated to the location shown in green to avoid problems later, should the foundation require retrofit construction later, or the pipes require repair.
Irregularly Shaped Corridors
"Irregularly shaped corridors" is the casual term that upFront.eZine gave to describe another CivilB feature, a term appropriate to a short article, but subject to interpretation. Allow me to explain.
When we reconstruct existing roadways for modification -- widening, adding streetscapes, introducing traffic calming, placing light rail in medians, modify segments of ditches and sidewalks, construct PCC pavement for bus bays, replace potholes -- we are involved in shifting pavement crowns, placing uneven thicknesses of overlay, widening pavements, all to conform to existing pavement and adjacent properties, and doing this mostly with non-continuous and irregular areas.
Civil3D and other civil engineering design software use alignment, profile, and cross section templates for their modeling approach. Civil3D significantly improved its flexibility in dealing with section templates by allowing assembly objects to model corridors and intersections of new roadway design. The current section template-based design software is effective at modeling surfaces along alignments with a certain consistency, but are cumbersome for modeling roadway reconstruction, grading designs with irregular or non-continuous or out-of-alignment surface features. Figure 2 illustrates an example of this.
Figure 2: An irregularly shaped reconstruction corridor.
The purpose of CivilB's 3D edge and PRS (parametric ruled surface) objects is to provide a flexible surface modeling approach for existing and proposed roadway/grading surfaces with regular and irregular features. See figure 3. We can use primary 3D edges to represent roadway centerlines or surface edges with controlling profiles and elevations. We can use secondary 3D edges to represent roadway edges whose profiles are determined from centerline profiles and cross slopes / super-elevations; alternatively, they can have independent profiles, and support variable cross slopes:
- Alignments and profiles of 3D edges can be related to civil engineering design standards.
- Pavement elevations between the 3D edges are defined by the mesh lines of ruled surfaces formed between two 3D edges.
- 3D edges and PRS objects can model parking lots, grading surfaces, and curbs and gutters.
Figure 3: 3D edge objects used to describe roadway features.
As pointed out in upFront.eZine, another reconstruction issue is the accuracy in calculating overlay quantities, because of fluctuations in existing pavement elevations and limited survey points. Our 3D edge and PRS objects allow us to tap directly into 3D pointcloud data from laser scan surveys directly.
[Bo Gao, PE, heads up XB Engineering Systems, an Autodesk Developer Network member, and developer of CivilB, a Civil3D partner product that provides additional tools for reconstruction projects.]
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Out of the Inbox
My travel plans for the next few months:
1. Wednesday, August 10: Siggraph 2011 in Vancouver, Canada
2. Thursday, August 18: LinuxCon North America 2011 in Vancouver, Canada
3. Tuesday, August 30: SolidWorks 2012 Launch Press Event in Concord, MA USA
4. October 4-5: Bricsys Developer Conference in Brussels, Belgium
DeelipMenezes on Twitter: "QOTD [quote of the day]: I have been looking forward to stress analysis software for Alibre. Now it appears I am getting stressed by analysis of Alibre ;-)"
Certainly 3D Systems' purchase of Alibre was the surprise news of the week, month. The surprise was that it was 3D Systems, not that Alibre was sold. You know a company is having an "interesting" time when its pricing plummets (to gain more customers) and then goes back up (to make an actual profit).
On KubotekUSA's "CAD Freedom and Precision" blog, Scott Sweeney wonders why 3D Systems bought a history-based parametric modeler, instead of a direct modeler. "Maybe they didn't really care about the flavor or CAD technology. They probably were most interested in the tens of thousands of potential new DIY'ers [do it yourselfers] to sell their newly acquired maker-bot hobbyist put-it-together yourself rapid prototyping system." http://info.kubotekusa.com/3D-Engineering-Software-Tools-Kubotek-Blog/bid/58014/What-will-Alibre-CAD-become
Actify announces SpinFire v10 at a lower price ($499 and up). New features include thumbnails of most-recently accessed files, minimum wall thicknesses within assemblies, calculations of projected areas of parts or assemblies, and new CAD interfaces. No-charge trial version from http://www.actify.com
Jon Peddie of Jon Peddie Research is the new president of SIGGRAPH Pioneers. "If you've been playing with pixels for the past 20 years or more, Mr Peddie invites you to become a member. Also: SIGGRAPH Pioneers' reception is in Room 302 at the Vancouver Convention Centre during SIGGRAPH in Vancouver, Canada on Tuesday August 9, 2011 at 18:00. If you're already a member of ACM, the Pioneers membership is only $5 extra." http://www.siggraph.org/programs/pioneers/home-page-and-announcements/
ralphg (Ralph Grabowski) on Twitter: "Vergence-accomodation is the pain created by 3D: eyes constantly adjusting between the distance to the physical screen and to the [apparent location of the] 3D image."
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These were the news items that was posted during the last week at our WorldCAD Access blog <worldcadaccess.typepad.com>:
- The Wengerd Report: New isn't always better by Owen Wengerd
- Jay Vleeschhouwer predicts the CAD revenues reports that begin next week
- Spatial CGM Capabilities Webinar
Letters to the Editor
Re: Spin Doctor of the Moment
"I read the Ballmer article, and was amused at some of his claims. For instance, when he compares 350 million units to a paltry 20 million [sold by Apple], he conveniently ignores the fact that Microsoft is NOT selling hardware, unlike 'those who shall remain nameless.'
"His claims on licensing are also amusing to me. Every new PC ships with a copy of Windows 7, so I don't doubt the accuracy. However, I work for an international engineering firm, and the very first thing the IT guys do with a fresh purchase is reimage to XP.
"So, even though however-many millions of Windows 7 licenses have been SHIPPED, how many are actually deployed in corporate environments? No doubt our company will move to Windows 7 or 8 eventually, but as of today we are firmly an XP shop. I would suspect many other large corporations are in a similar situation."
- Robert Melnyk
The editor replies: "Of the 350 million, 250 million were copies shipped with PCs, so that would be the suspect portion of the number -- as people stay with XP or even Vista. (I found that Vista worked really well after SP1, and that 7 caused me more grief than did Vista, but then it was too late to go back.)
"The large number also papers over the dismal Windows sales on devices that now matter, like smartphones and tablets. Given the choice, people avoid Microsoft software; the exception is XBox, but only with a multi-billion-dollar loss.
"Despite this, I still prefer Windows over OS X. I have to use a Mac for some of my ebooks, and I find that OS X feels sluggish in comparison to my PC, perhaps because it lacks things like ReadyBoost and a clear insight into graphics handling. Hardware and software corporations have told me in confidence that Apple has no clue about the importance of an efficient and well-documented graphics pipeline between graphics boards and apps, yet dare not speak out publicly for fear of being cut off by Apple."
Re: Arup MassMotion:
"It's very bad that SketchUp is neglected. It is definitely not for an amateur or designers who experiment or small companies, and absolutely not for Indians. India, where I come from, is so largely populated (next only to China), and has the least vehicle-per-person ratio, with heavy pedestrian counts."
- Jubair Siddeeque
"The stuff about crowd and pedestrian flows is interesting. The closest I have come to working with that is herding cattle, and it was kind of a revelation when it finally sunk in that, deep down, I was assuming that they flowed like water. They don't. When I quit laying out corrals and pens like that, and started understanding the things that Bud Williams and Temple Grandin write about cattle psychology, life got easier.
"You wrote, 'In countries that drive on the left side of the road, elevators run the other way...'. Wait, they run sideways?"
- Jess Davis
Re: Death of Dennis Jeffrey
"Sorry to hear about Dennis. He was much too young to leave us. My condolences to his family."
- Chris H
Re: Celebrating the 700th Issue:
"Happy 700th! Although that makes you seem old!"
- Robin Capper, rcd.typepad.com
"Congratulations on reaching 700 issues. An impressive effort."
- Mike Burke, New Zealand CAD manager
"I now have to halt my CAD work. Am now 77 and unable to do things like the good old days. Thanks for your articles."
- Jack Birdsall
Spin Doctor of the Moment
"Many audacious projects lie flat on the table waiting to be developed and released."
- PanaVue Inc. (H.T. Don Beaton)
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Entire contents copyright 2011 by upFront.eZine Publishing, Ltd. All rights reserved worldwide. Letters sent to the editor are subject to publication. Article reprint fee: $250 and up. All trademarks belong to their respective holders. "upFront.eZine," "The Business of CAD," and "WorldCAD Access" are trademarks of upFront.eZine Publishing, Ltd. Letters to the editor may be edited for clarity and brevity. Translations and opinions expressed are not necessarily shared by upFront.eZine Publishing, Ltd.