Hi,

The intention here is more to provide a 'priority' for expiring children.
The case I have is, when viewing a very detailed terrain, my models are being 
expired immiadiately while some of the terrain tiles are not. My solution does 
not implement a proper priority but it does result in the desired outcome.

As some background, I was originaly using the 
'setNumChildrenThatCannotBeExpired' (which already exists) so the models where 
never expired, but this results in a permanent 'memory leak', rather than one 
that lasts for 30 seconds or so.

Essentialy I want the models to be the last thing expired as they are 
relatively slow to page in and don't have a good fallback LOD. Idealy the 
models would be better designed but I am required to support kml models from 
googlewarehouse, which means (even after scaling textures and using the 
optimizer) many, often badly designed, models being displayed. 

In relation to your comments, if you have any further thoughts on controlling 
memory use I am happy to dive in and try and implement some improvements. I am 
constantly battling memory constraints on our 32 bit builds as there is a hard 
limit of ~2gig per process under windows and I share the process with a 
heavweight Java application and VM. Even when I run the 3D component standalone 
I get out of memory errors using the default VPB terrains when viewing large 
areas of high detail map data. I have improved this dramtically by implementing 
my own scheme for deciding which child of a PagedLOD should be active (based on 
a mix of distance and viewing angle ), but am very keen to regain some control 
of memory use.

Idealy, it would be great to be able to set a hard limit on memory use and 
higher LODs simply stop loading if this limit is reached.

Cheers,

Brad

-----Original Message-----
From: [email protected] 
[mailto:[email protected]] On Behalf Of Robert 
Osfield
Sent: Tuesday, 18 October 2011 3:36 PM
To: OpenSceneGraph Submissions
Subject: Re: [osg-submissions] Small enhancement to PagedLOD

Hi Brad,

I haven't reviewed the submission yet but it does make me nervous that
you want a means of bypassing the DatabasePager's standard maximum
number of PagedLOD.  If your application has the space to maintain
more PagedLOD then the appropriate thing would be to up this limit to
encompass the maximum number - this would result in more PagedLOD
being kept around on average than your suggested scheme.

One thing I have considering is changing the default
MaximumNumberOfPagedLOD for different platform targets - so embedded
space this number would be kept small but for normal desktop targets
allow this figure to go up.  Perhaps if we had a scheme for checking
available memory on a system we'd be able to compute this
automatically.

Robert.

On Tue, Oct 18, 2011 at 6:06 AM, Christiansen, Brad
<[email protected]> wrote:
> Hi Robert,
>
>
>
> The attached files add the ability to control when a paged child becomes
> eligible for expiry based on time and/or elapsed frames.
>
>
>
> I found that some of the items that had been paged in were being expired on
> the first frame that they were not visible (as the cache was full). This
> resulted in excessive paging every time the view was moved. With the
> following changes I could only allow children to be expired if they had not
> been used for e.g. 30 seconds or 60 frames.
>
>
>
> The changes were made against trunk revision 12822.
>
>
>
> Cheers,
>
>
>
> Brad
>
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