PUSH/PULL inaccurate measurements?

Hi,

I’m new in this forum, just done some reading before. I have worked with SU pro for a few years, I make house drawings.

I have come across an annoying little problem, my measurements don’t ad up in the nano scale (metric system). Its 0,0000001 millimetres, or something, wrong at times. Always correct when I type the measurement, but sometimes incorrect when I use the push/pull tool or move tool.

When using the precision 0,00 mm in SU it’s all fine visually, but when importing to AutoCad I immediately see it. Because AutoCad have the default precision of 0,000 mm.

I’m pretty sure no buildings will fall down by this and it’s not a “real” problem, but its amazingly annoying for my sense of order!

Anyone have a solution or tips to share?

Do you have Length Snapping enabled?

Have you got any measuring devices that could measure to 0,0000001 millimetres in reality?

You (usually) need to type it with those tools too, in order to get accuracy, especially without an accurate inference point. So simply, when you push/pull or move, type your measurements (don’t just drag and assume the displayed measurement is perfectly accurate).

A human hair is .08 mm… so you are talking about a thickness of a fraction of a fraction of the with of a human hair… I would recommend not trying to model to that accuracy, anyway… most materials swell or contract more than that based on temperature and humidity :wink:

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You can set the precision in SU to match the AC default precision of .000mm, or you could set it even higher in SU. Then you can monitor which operations you are doing that are changing your geometry. Again: turn length snapping off, and watch for the tilde with any measurement which indicates that it is rounded. There is no reason you cannot model to the level of accuracy you want in SU.

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Maybe, if you share the model.
are the axes slightly rotated? See if ‘Reset’ is available in the right click context menu when clicking o an axis.
Again, please share the model.

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I have made some SketchUp (SU) modelling after importing AutoCAD drawings that showed dimensions rounded to the nearest millimetre. However, SU showed these as 2999.999999 mm or 3000.000001 mm for example. So, AutoCAD is not better or worse than SU. All softwares have rounding errors. Especially when they are programmed to use one system of units as default and allow another system as an alternative.

And, as pointed out by others, using super precision is not required in many fields. For example, on industrial projects, we specified that piping, for example, be positioned with a precision of 5 mm (about 1/4 inch) from the intended position shown on the drawings.

If you don’t want to see funny numbers like the one I mentioned above, set your precision to a less demanding value. SU is always using the maximum precision even if the displayed values are rounded.

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Hi everyone! Thank you for the replies.
I’m aware this is not a real world problem, as stated in my first post.
I would absolutely love to have a nano accurate laser measurement tool :laughing:

The first time I noticed my accuracy predicament was 2017 and I’ve been wondering ever since. Now I finally have time to investigate! :slightly_smiling_face:

I do have the snap activated in SU, will try turn it off in the morning.

And maybe being more careful when choosing what edges, surfaces or lines will help too.

Length Snapping is often responsible for inaccurate dimensions in SU. The general advice is to turn it off.

SketchUp stores its measurements in inches. Not every metric measurement can be exactly converted to inches and then back to metric. I suspect that your original numbers got lost in translation.

The solution is to type the distance measurement while you use Move or Push/Pull.

I have often been thinking whether this is the reason behind some of the odd small errors that sometimes come up in models but I haven’t found a way to test it. After all. 1 meter is 39,3700787401575 inches and I don’t think it is stored as accurately as that.

On the other hand, although one could argue about the current value, that’s why SketchUp has the nearby vertex and cleanup threshold.

they should let us store it as millimetres instead of only inches. More accurate.

I notice some strange reactions about hair and reality. That not the point like the OP stated. It’s about accuracy. SU offers the precision.

I notice it too, specially when doing some 3D small work, certain shapes will never becoming a solid object. If I draw it 100 times bigger ( upscaling ) the it does. Special the snap function, it fails often.

Thank you for all responses!

So, I have tried to replicate my errors and I believe my use of guidelines may cause the slight measurement imperfections and snapping should absolutely be turned off.

Push/pull or move to edges and surfaces works just fine, when focused on the task.

The main cause, in my opinion, for inaccuracy is trying to work to fast. Maybe it’s a small compromise, compared to the output in the factory.

Computers typically don’t make calculations at such precision. At the smallest scale there will always be a little noise in SketchUp. In my own projects I think I’ve never shown more decimal places than hundredths of millimeters, and then I only really use tens of millimeters for my measurement and show an extra digit to make sure it rounds to 0.

I don’t think this would make much difference. Fractional values like 1/3 or 1/10 (in binary) need an infinite amount of digits to be perfectly reproduced. A factor of 25.4 isn’t any worse.

Highly doubtful. If you place your guidelines accurately there should be no discrepancy. When you move and push/pull do you type in the desired dimension? All you have to do is make sure you type it and it won’t be off at all.

Guides can cause issues when placed inaccurately.

Right. That’s why I’m advocating he always types his measurements so there is no discrepancy. The only reason for a fraction of a millimeter off is that something isn’t placed precisely. Maybe he’s just eyeing it. I’ve suggested simply typing the dimension when using push pull and move several times because that is the one and only solution. All this talk about how it’s not a big discrepancy is, to me, pointless.

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That’s the spirit !
+1

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