Thursday, July 21, 2011

When Is a Foot Not a Foot?

I ran into an interesting issue today when dealing with some survey drawings that were done in both metric and imperial units.  Not something you run into every day but for me, today was that day.  As Civil 3D users know, Civil 3D understands that there are U.S. and International Feet.

AutoCAD, however, does not.  So even though you may have leveraged Civil 3D's ability to distinguish between different types of feet through LandXML, Survey Database, etc., if you do an XREF or insert a block and you're depending on the AutoCAD INSUNITS system variable to kick in, you might find some discrepancies.

By the way, International feet are .3048 meters while US Survey Feet are 39.37 inches per meter or 12/39.37 or 0.30480060960121920243840487680975 meters, give or take.  When dealing with large coordinate values (like state plane coordinates), this starts to make a difference.

So, what do you do about XREFs or inserting blocks.  Well, the best approach I have found is to turn off the effect of the INSUNITS system variable by setting it to zero.  Then, when you insert or XREF a file, AutoCAD won't do you the favor of trying to scale it for you.  Then once it's in there you can use the SCALE command with a factor of 1200/3937 to go from feet to meters, or the inverse of that to go from meters to feet.

Beware of another favor that AutoCAD tries to do for you.  There's a setting in options that will just go ahead and assign a scale factor for your incoming block or XREF even if you've said you wanted it to be unitless.  It's on the User Preferences tab under Insertion Scale.  AutoCAD is like that over-helpful store worker who keeps saying "Can I scale that for you?", "Can I scale that for you?".  No AutoCAD, I got it.

Do you use a different approach to handle this issue?  If so, please share.

Wednesday, July 6, 2011

Daylight Rounding

OK, so once again I'm bearing my soul about something I should have known but didn't because I'm thinking; if it happened to me, it happened to someone else and hopefully that person will read this.
Anyway, at the Subassembly Composer sneak peek yesterday I inquired about Daylight Rounding.  I asked if it was a feature available only in the SAC?  It was brought to my attention by the illustrious Nick Zeeben that, to my surprise, it's been in Civil 3D since like 2009!  Luckily I've been doing this too long to get embarrassed about such a thing so I chalked it up as one of those hmmmm moments.
Anyway, if you're clueless about this feature, like I was, you'll find it as an option in all (I'm assuming all, I didn't check every one) of the daylight subassemblies.

So the way to apply it is pretty simple (these values are based on the BasicSideSlopeCutDitch subassembly BTW):

  • First, say Yes to rounding by choosing Circular or Parabolic for the Rounding Option instead of None
  • Choose Length or Radius as the Rounding Parameter by choosing either option beside Rounding By
  • Enter a value for the Rounding Parameter (length or radius)
  • Enter a value for Rounding Tessellation - another case where you can't really draw a curve in Civil 3D so you have to tell AutoCAD how to break it up.
Once you've done all that you should see some nice, rounded daylighting in section view...

And those little hooks on your contours that everyone loves so much

So to make myself feel better I've decided that I didn't know about this because when it comes to daylighting, I like to keep it as simple as possible and usually try to get by with LinkSlopeToSurface (which has no Rounding option).  Frankly I think Civil 3D needs a simple daylight subassembly that has no ditches, linings, alternate slopes, bells, or whistles. It just daylights using one of two slopes: cut or fill.  Maybe call it DaylightICanUseWithoutGettingAHeadache. Can I get an "amen"?

Tuesday, July 5, 2011

Subassembly Composer - What Does it All Mean?

Information about the Subassembly Composer (SAC) that will become available to subscription customers this week is already flowing.  So rather than talk about the details of this tool, I thought I would talk more about how I see it playing out within the firms that use Civil 3D.

First of all, I think that the release of this tool is HUGE.  It opens up an infinite number of doors to the types of designs to which corridors can be applied.  In fact, within the short hour that it took for Autodesk to provide a sneak preview of the tool, I saw an I-beam, a breakwater, a retaining wall, and of course a few roads (although highly specialized roads).  As for the tool itself, I have to say "Nice job, Autodesk".  It is robust and as user-friendly as such a tool could be.  It is an example of why to be on subscription.

However, composing subassemblies (heck, even spelling subassemblies) is not for the casual Civil 3D user.  Think of composing music.  Anyone can listen to music (using assemblies), a lot of people can play music (build assemblies), but only a handful have an understanding of music that enables them to compose music (make subassemblies).  In a typical company, I think that a small percentage of the users will have the mettle or the desire to build subassemblies.   Many will be curious, some will tinker, but only a few will actually build production subassemblies.  There is absolutely nothing wrong with that, but I think that's the way it will be.  In fact, having a small number of people creating custom subassemblies and controlling their consumption might be a good idea to avoid reinventing the wheel.

That said, the fact that only a few will use it does not make it any less useful or important.  Why?  Because even though creating custom subassembiles is a bit tough, it is now much more accessible.  It is something that anyone can at least try, even if they have no programming experience.  And the ability for each firm or organization to be able to create its own custom subassemblies has the potential to remove nearly any limitation currently presented by the use of stock subassemblies.

So why am I telling you all this?  To help you set expectations and not waste time on what you think this tool might be.  It's not a magic wand that you can wave that will create a subassembly at the push of a button. Building subbasemblies, even with a tool as slick as this is going to take work.  My advice:  If you need custom subassemblies and you're a casual user, forward your info on SAC to your office Civil 3D guru and take him or her out to lunch.  If you're a Civil 3D guru, install it (when it becomes available) and give it a try.  If you feel overwhelmed, look to someone you who is even more of a guru than you.  Or, be patient...I'm sure there will be training content available soon.  Oh, and the Autodesk WikiHelp content for this tool is already well-populated.

Happy composing!