AutoCAD’s 64-bit precision has been discussed and documented for years and hailed as the most technically precise system for many years since the eighties. This was long before people realized that some would actually need even more precision in the floating point calculation provided by the then math coprocessors and then in the 32-bit platform. There was an example demonstrated by Jon Walker the founder of Autodesk with a AutoCAD drawing showing a to scale of the universe. In this drawing of the universe you could zoom in on the moon and see a moon lander with a plaque and text on it. The drawing has many named views for the locations in the solar system and I have resaved it in AutoCAD 2004 format.
Screen capture of the solar drawing. All images can be clicked on for a larger version in a pop up window. You can also download the drawing from Here
To demonstrate the limitations of the 64-bit floating point I created a polyline with an arc (bulge) next to the moon lander plaque. Now because we are 1.499E+08 (149900000.0) from 0,0 or located at the coordinates of X=-1.205E+08 Y=8.921E+07 if we try to offset this polyline the small radius bulge will round to 0 due to the limit of digits in the floating point of the processor for calculations. So the limitation is if you have an object a very great distance from the origin coordinate of 0,0 the limit of 15-16 digits calculations could result in unexpected results. Of course by simply moving this object temporarily closer to the origin of 0,0 the offset works perfectly because less digits are used in this calculation and no rounding issues.
Screen capture of the polyline near the plaque.
Screen capture of the polyline after Offsetting .0001 and the unexpected result.
Screen capture of the polyline after Offsetting when the plaque and polyline were moved to 0,0 at the center of the sun. The offset is as expected and correct.
What does this all mean?
If you are designing a small micro circuit board on the surface of mars, move the part closer to the 0,0 when using operations that require system calculations such as Bhatch, Offset, and so on. Well AutoCAD uses the most precision it can and has since the eighties but with new technology in processors coming we will continue researching to see if we can get even more precision in the extreme conditions.
Explanation on the accuracy by the late (and greatly missed) Alex Januszkiewicz
Sincerely,
Shaan Hurley
Hi Shaan, about the solar system drawing, I tried to DWF it but no way. It seems the accuracy of the DWF is not great enough to represent the smaller objects, in that case, the planets and the text is invisible or distorted.
Any way to make a DWF out of this DWG so that both look the same?
Wow, that drawing is a blast from the past (excuse the pun!). I remember opening that drawing back in the 80’s (I think). Which version of ACAD did it come as an example drawing?
Mike, “one of my favorite Kiwis who is now in Summer weather”
The drawing was in AutoCAD 2.18 DWG dated 4/5/1985 , also in 2.5 & 2.6. I just ran them to verify ;-).
There was also a MNU file:
**SCREEN
[System]^Czoom e
[Inner]^Cview r INNER-PLANETS
[Sun]^Cview r SOL
[EarthSys]^Cview r TERRESTRIAL-SYSTEM
[ Earth]^Cview r TERRA
[ Moon]^Cview r LUNA
[ Crater]^Cview r LANDING-SITE
[ Lander]^Cview r LANDER
[ Plaque]^Cview r PLAQUE
[Planets]$S=PLANETS
[VIEWLIST]^Cview ?
[VIEW]^Cview
[PAN]^Cpan
[WINDOW]^Czoom w
[MAGNIFY]^Czoom
[Exit*]^Cquit y
**PLANETS 3
[Mercury]^Cview r MERCURY
[Venus]^Cview r VENUS
[Earth]^Cview r TERRA
[Mars]^Cview r MARS
[Jupiter]^Cview r JUPITER
[Saturn]^Cview r SATURN
[Neptune]^Cview r NEPTUNE
[Uranus]^Cview r URANUS
[Pluto]^Cview r PLUTO
[EarthSys]$S=SCREEN ^Cview r TERRESTRIAL-SYSTEM
***BUTTONS
;
zoom w
Cheers,
-Shaan
I am taking an AutoCAD course at Bristol Community College in Fall River, MA. and my instructor Mr. Richard Horton just showed us this drawing today as an example of how powerful AutoCAD actually can be. We were told this was done in DOS and probably took close to one year to complete this project. Is this for real? Wow, what dedication and accomplishment, thanks to the creators.
PING:
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BLOG NAME: Between the Lines
Back in AutoCAD version 2.18, Autodesk placed a sample drawing with AutoCAD named the Solar.DWG to demonstrate the precision of AutoCAD back in the early eighties. AutoCAD was based used 64bit floating point precision and the most accurate back then. W…
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TITLE: The Solar System Drawn to Scale in AutoCAD DWG- Scale is Everything
BLOG NAME: Between the Lines
Back in AutoCAD version 2.18, Autodesk placed a sample drawing with AutoCAD named the Solar.DWG to demonstrate the precision of AutoCAD back in the early eighties. AutoCAD was based used 64bit floating point precision and the most accurate back then. W…
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BLOG NAME: Between the Lines
AutoCAD HATCH objects are probably one of the most commonly used of the AutoCAD objects, but they do have some limitations and reported issues. We are looking for examples of problems with AutoCAD HATCH objects so we can research further
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TITLE: Celestia shows space is big and beautiful
BLOG NAME: RobiNZ Blog
In 1983 John Walker drew the The Solar System to scale in AutoCAD-86. It was a demonstration of AutoCAD
PING:
TITLE: Celestia shows space is big and beautiful
BLOG NAME: RobiNZ Blog
In 1983 John Walker drew the The Solar System to scale in AutoCAD-86. It was a demonstration of AutoCAD