ldd memory crash

[nullbyte]

Hi,

I'm trying to import a huge lxf model into LDD. It starts loading but when LDD's memory usage gets to exactly 1.5GB the program crashes. My computer has 12GB of ram. Is it possible to fix this crash or to increase the amount of memory that LDD can use?

Thanks!

[Brickdoctor]

I am by no means an expert in this field, but I do know that the people who can help you will probably need to know the stats of your CPU, GPU, and OS.

[DLuders]

Did you read this "pinned" topic first? Do you have the LDD Enhanced Graphics option turned ON or OFF?

[nullbyte]

I am by no means an expert in this field, but I do know that the people who can help you will probably need to know the stats of your CPU, GPU, and OS.

CPU: Intel Core i7-930

GPU: ATI Radeon HD 5870

OS: Windows 7

Advanced Graphics: Off

Edited July 15, 2011 by nullbyte

[DLuders]

@ nullbyte: There was this related Eurobricks topic about computers crashing when loading large LDD files. Alienwar9 (who is building a HUGE cityscape in LDD) said this here:

"What might be the real issue is memory, both RAM and cpu. Once again my technical knowledge is small, but my guess is that the giant calculations send data to the cpu to process, and it gets bottled up in the bus before the cpu can even handle everything, so even if you cranked up the processing speed of the cpu, too much data is sent at once. LDD uses huge amounts of memory when models get big, but I noticed that long before my memory gets capped out (LDD maxes out maybe at 75% of total RAM; including other processes) LDD will slow/crash/hurt. So I don't think RAM is the main issue, but its definitely indicative of what could be the problem, extremely large calculation sets. Also, I've had instances where I've made a move that has crashed LDD after longer successions of moves, that after a restart LDD had no problem with. LDD tends to build up its memory usage with further actions (another example, I've used the undo button and LDD has crashed)."

Bojan Pavsic added this: "As you correctly found out, moving lots of parts really slows down, since the count of calculations goes up really fast.

For example (without any optimization): if you have like 200 bricks with 1000 free connection points and you move 1 brick with like 10 connection points, that's about 10.000 checks (1000 x 10). On the other hand if you move 10 bricks with like 100 connection points, that's 100.000 checks (10x more -> 10x slower). With a "normal" refresh rate of like 25fps (and that's pretty low), that's 2.5 million checks (again... without optimization, with fictional numbers).

And this is just for connection points. Then there's the geometry overlaps, which of each of the bricks has A LOT (thou probably the first check is overlapping the border boxes first, which is quite fast)."

SO, there is a limit to the file size that LDD can handle. Recommend breaking up your LDD model into smaller "groups". At 30,000 bricks or more, you're probably going to crash LDD....

Edited July 15, 2011 by DLuders

[Judah Nielsen]

Bojan Pavsic added this: "As you correctly found out, moving lots of parts really slows down, since the count of calculations goes up really fast.

For example (without any optimization): if you have like 200 bricks with 1000 free connection points and you move 1 brick with like 10 connection points, that's about 10.000 checks (1000 x 10). On the other hand if you move 10 bricks with like 100 connection points, that's 100.000 checks (10x more -> 10x slower). With a "normal" refresh rate of like 25fps (and that's pretty low), that's 2.5 million checks (again... without optimization, with fictional numbers).

And this is just for connection points. Then there's the geometry overlaps, which of each of the bricks has A LOT (thou probably the first check is overlapping the border boxes first, which is quite fast)."

I've often wished for the ability to somehow paint connection points. Tell LDD exactly which bricks from each subassembly need to connect, and then let it work out whether I've got a legal connection. My least favorite part of assembling a large model is trying to coax one of the imported sections into exactly the right position with respect to the rest.

[Superkalle]

Did you read this "pinned" topic first? Do you have the LDD Enhanced Graphics option turned ON or OFF?

This is a valid point that DLuders is making.

Having Enhanced graphics turned on makes a big differnce in the likelyness of a crash. I had a model with 50.000 bricks crash LDD with enhanced graphics on, but it loaded with them off.

I've often wished for the ability to somehow paint connection points. Tell LDD exactly which bricks from each subassembly need to connect, and then let it work out whether I've got a legal connection. My least favorite part of assembling a large model is trying to coax one of the imported sections into exactly the right position with respect to the rest.

A trick here is how you select the bricks.

If you have a large subassemly that is to be attached/placed to main assembly at a certain position, then do like this:

1) Select the subassembly, and then click on the brick that you want to attach to the main assembly. (i.e. where you click on the subassembly matters)

2) Now, move the mouse to the position where you want to connect the bricks. With large assemblies you have to wait a while to see the movement. From here you may need to nudge/re-position slightly a few times.

For this to work, you need to orientate the subassembly and the main assembly in such as way that you can see both the "source" brick and the "target" brick.

Hope it came across roughly what I meant