[SOLVED] How to improve performance on very large drawing?

[danbr]

I have a VERY large drawing - the original DWG is 5Mb, and the DXF as it saves with no changes is approximately 12.5 Mb and about 4500 elements. A large percentage of the elements appear to be splines. It's actually a detailed exterior drawing from Ford of a Ford Transit van, including sections, roof plans, and front/rear/side elevations.

I tried splitting out part of it (just the roof plan), but the performance is still horrible. As an example, unlocking a layer containing most of the drawing takes between 30 and 40 seconds! The roof plan alone is about 1400 elements; many of them are splines. I did go through and remove the unused blocks (many!) and layers, with no noticeable change in speed.

System is OpenSUSE Linux 64-bit with all current patches running on a quad-core i5-6500 3.2Ghz with 64Gb of physical memory. I'm running QCad Pro 3.25.2. During the long delays, it appears that qcad-bin is using 100% of ONE core (ie, 25% of my available CPU cycles) and between 6% and 10% of the available memory. Swap usage is 0.

I'd be happy to post the roof plan portion if it's not too large - about 4.5Mb.

Any suggestions about how I might improve the speed of typical tasks while working with this drawing???

Thanks!

Dan

[Husky]

Hi Dan,

I'd be happy to post the roof plan portion if it's not too large - about 4.5Mb.

Yes please - attache the drawing to your post so that we can discuss what could be done.

[CVH]

Hi, and yes please.

A dwg with 4500 items making up 5Mb intrigues me/us...
'elevations' make us wonder if there are non-zero Z values.
'30 - 40 seconds!' to unlock a layer with about 4500 items is not considered normal.

Question: In Model_Space?

Question: Does QCAD report unsupported items when loading the file?

Question: What kind of splines?
2 types are QCAD native, I am aware of a third type supported.
Type 3 are in fact chains of Bézier Curves.

Already reported and I have also endorsed it again that after an AutoSave, speed can decrease vastly with such files.
Here with hatches: viewtopic.php?f=30&t=7842
(A hatch is made up of numerous individual segments, here the grandtotal is over 1M)

Unused Blocks, nor empty Layers contribute much to delay. A vast amount of items do.
The Block/Layer structure itself can make it troublesome to render.

Mouse actions can be slow with big files, keyboard can be quicker.
E.g. zooming with [+] & [-]

An example would tell us more ... Maybe.

Regards,
CVH

[danbr]

OK, the extracted roof plan is attached. The splines all show up as "Spline [1]" in the property editor. I also ran Misc -> Modify -> Flatten Drawing to 2D, but (once again , no noticeable performance change.

Model_Space: Yes
Errors or unsupported types while loading: No

For my own purposes, the outlines here have been split into two layers, but they were all on one layer in the original drawing.

Thanks VERY much!

[danbr]

If it would help the diagnosis, I can also upload the original DWG - it's Autocad R14.

Dan

[CVH]

Hi,

OK the file loads slow and there is a 'medium' lagging.
But it seems I have less problems with that still using 32bit.

1) A quick review showed that some/many/all splines use a specific LineType ISO dash. (872 as is)
QCAD has to render all the dashes ...

In CAD it is usually the layer that defines the properties apart that exceptions could use a specific property.
https://qcad.org/en/tutorial-working-with-layers
Viewing all:
- 1408 exceptions on LineType.
- 1108 exceptions on LineWeight.
- 232 exceptions on Color.

On top: Layer 'vehicle_roof_background' uses dashes too.

Once I altered all to by Layer and set all layers to continuous the performance went up considerable.
Now it depends largely on how much I see from the drawing.
Up close the mouse works fine.
Not up close the keyboard is a better option.

2) About 800 Splines do use degree 5 and in some cases it is even obvious they don't display correct.
Changed all to degree 3

Now the file works as a charm.


Regards,
CVH

[danbr]

Very cool, thanks very much!

How did you identify and change the spline "type" - I don't see that in the manual (or the UI ) Or is that the "Degree" setting in the Property editor?

I'll put the dashed lines in another thread . . .

Dan

[CVH]

Or is that the "Degree" setting in the Property editor?

Exactly, the degree of a spline.
> Selection filter ... Select and alter the degree.

But by this the drawing is no longer the same at some places.
While at others places it made more than sence to do so.
Still there are fuzzy splines, look close now you can navigate better.

Regards,
CVH

[danbr]

Ahh, thanks! I couldn't figure out how to display the selection filter, but I've got it now!

[CVH]

Very powerfull tool.
CVH