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Partial Loading vs Lightweight Representation

Valued Contributor
Valued Contributor

In an assembly, what is the difference between Partial Loading and Lightweight Representation??

 

We have always used Partial Loading, but that is causing issues now. Assemblies now show up out of date (!) using partial loading. Parts list changes will not keep using partial loading.

 

If I switch to using lightweight representation only, all shows up fine.

 

Just curious to what the difference is, before I have us swith to not using partial loading.

 

NX8.5.3

18 REPLIES

Re: Partial Loading vs Lightweight Representation

Siemens Phenom Siemens Phenom
Siemens Phenom

This issue was a PITA for us in all versions of NX 8.5 and earlier.  It seems to have gone away in NX10 or at least became less frequent.


Larry Carpenter, P.E.
CAxPLM Architect @ Siemens Molecular Imaging
Past Board Member @ PLM World, Inc,

Re: Partial Loading vs Lightweight Representation

Siemens Phenom Siemens Phenom
Siemens Phenom

While these two concepts, Partial Loading and Lightweight Representations, are totally different in terms of what's happening, they are both options that will help in improve performance and reduce needed memory when working with large assemblies.

 

Partial Loading limits the amount of data that is loaded when Components are opened as part of an Assembly.  For example, expression data, Hidden objects, non-displayed objects, etc are NOT loaded when a Component is loaded as part of an Assembly.  This data is only loaded when that Component is made the Work Part either in the context of the Assembly or as the Displayed Part.

 

As for Lightweight Representations, this only effects what sort of data is loaded in order to create the displayed model.  Ever since NX 7.5 all Part models now contain both an Exact Representation of the Solid and Surface models as well as a Lightweight (i.e. faceted) version.  This Lightweight version also contains the so-called LOD (Levels Of Detail) model data which can be used to provide even faster display performance when the display of large Assemblies are being dynamically manipulated on the screen.  When Components are load using the Lightweight Representation option, irrespective of the Partial Loading option, only the 'facet' data will be used to display the Component as long as it's NOT the Work or Displayed Part (in those case the exact representation is used).

 

Now it is true that because some of the data, such as WAVE links and Interpart Expressions may not be fully loaded when using Partial Loading, that this can impact whether an Assembly is marked as up-to-date or not.  Over time there has been an attempt to mitigate this impact so with later versions of NX this should be less of an issue.  Now there is no impact whatsoever with respect to whether an Assembly is flagged as up-to-date or not when using the Lightweight Representation option.

 

So my advice (for what it's now worth with my new status) is to ALWAYS enable to the Lightweight Representation options and to use Partial Loading only when performance or memory usage is a critical issue when working with very large Assemblies.

John R. Baker, P.E. (ret)
EX-Product 'Evangelist'
Irvine, CA

Re: Partial Loading vs Lightweight Representation

Phenom
Phenom

@JohnRBaker wrote:

So my advice (for what it's now worth with my new status) is to ALWAYS enable to the Lightweight Representation options and to use Partial Loading only when performance or memory usage is a critical issue when working with very large Assemblies.


Then is not so difficult to adda setting where up 500 components, NX open assembly in 'Partial loading' ? SolidWorks do that from 2003.

Thank you...

Using NX 11 / RuleDesigner PDM

Re: Partial Loading vs Lightweight Representation

Phenom
Phenom

UG-NX 'invented' partial loading!

I have used UG-NX since 1994 and I have always seen partial loading flag!

Re: Partial Loading vs Lightweight Representation

Siemens Legend Siemens Legend
Siemens Legend

Smart Lightweight which from memory came in NX 7.5 timeframe also enables certain functionality to be performed on lightweight bodies, most notably drawings, so if you have large assembly drawings then make sure "Load Smart Lightweight" is set in your customer defaults.

 

 

Paul

Re: Partial Loading vs Lightweight Representation

Valued Contributor
Valued Contributor

Paul, found that out the hard way. Had it turned off, our supplier said to, and drawings wouldn't come in. Trial and error found that was the only change made, turned it back on and drawings open ok. But thanks for the info.

Re: Partial Loading vs Lightweight Representation

Valued Contributor
Valued Contributor

John,

Please define "very Large assemblies'.

Performance is always an issue, when trackball response is slow, it causes issues during customer reviews. Our assemblies range from Station Asm - 3000KB, Die Asm 13,000-20,000KB, System Asm 40,000-80,000KB. That is why we are looking into options for large assemblies.

Re: Partial Loading vs Lightweight Representation

Siemens Legend Siemens Legend
Siemens Legend

Jadodaro,

The definition of a Large Assembly is always difficult, what is large to one company maybe small to another. There are tools in NX to allow you to manage complex assemblies, the use of lightweight geometry being one. One question is how often do you need to load the complete assembly? During the design phase it may be practical to just load the information you need for a particular task and NX has a number of tools to manage this type of process, such as creating component groups or zones or loading by proximity. Some of these tools are only available in NX Advanced Assemblies however.

As for trackball/spaceball response there is a setting in Preferences - Visualization Performance - Large Model, that allows you to set parameters that control the display of geometry during rotation and when stationery, you can set it that certain geometry temporarily disappears speeding up rotation, zoom and pan. Take a look at the Custom Setting.

 

Regards

 

Paul

Re: Partial Loading vs Lightweight Representation

Siemens Phenom Siemens Phenom
Siemens Phenom

It's all relative and there are also different issues relative to the options being discussed.

 

For example, the issue of 'Partial Loading' is related more to the amount of data that you need to access when opening an assembly, which is impacted by several issues some of which has nothing to do with the actual assembly itself.  These include the speed of your hardware, the amount of physical memory available and even the type of storage and location of your servers.  Having local solid-state storage (i.e. SSD drives) will make it less problematic when opening large assemblies than if you had to move that same amount of data over a network from a remote server for example.

 

As for the 'Lightweight Representation' option, that's more related to the actual topology of your models (lots of freeform faces versus simple prismatic parts) as well as the performance of your local graphics, again something that could be impacted by hardware speed, but perhaps not as much by what sort of storage or whether it's remote or not.

 

There are many variables that will impact what constitutes a 'large assembly' and since many of them are not something the NX itself can control, that is why these options and settings are provided to the user but it's also why there is not a "one size fits all" solution.  If there are issues related to the topics I mentioned above, then experiment a little and see which options and settings seem to help the most, but don't be afraid to change your approach as the size of your models change or when your hardware is updated or refreshed.

John R. Baker, P.E. (ret)
EX-Product 'Evangelist'
Irvine, CA