[Bf-committers] Problem of Rendering Speed

[Yaohua Xiong]

Hi Beihong,

It's nice to see you too. The very reason behind considering using
particle system is efficiency. What I'm trying to do is not visualize
2000 cars but 100000 cars. The 2000 cars problem can be solved using
the first method(objects+ipo) with no problem, but the 100000 cars
problem must use memory more efficiently, like creating cars on the
fly when it's entering the road network ,recycling cars out of range,
cache file swapping in/out memory, etc. To fulfill these needs, use
the particle system should be easier than other way.

As for the feasibility of the particle approach, I think it's not a
problem. With jahka's latest add to particle system---external
particle cache file---It's possible to control each particle's
behavior once you have an external package to generate them. Current
what is missing is how to give these particles some variation in
appearance.

On Tue, Aug 4, 2009 at 11:54 AM, Ruan Beihong<ruanbeihong at gmail.com> wrote:
> Hi Yaohua,
> It's good to see chinese (I'm one too) in the maillist. I'm an
> undergraduate in Wenzhou Medical College.
> I'm neither an artist nor a tech guy. I use blender mainly to edit
> some DV clips.
>
> In my humble opinion, the particle system should not be used in this way.
> Particles usually simulate something emits light and spreads randomly
> on small scale but move regularly on large scale.
> It's not proper either to control every particle in the system (I
> wonder if it can be done even), nor to build thousands of
> particle system in one scene. If I'm right (I'm not quite sure as I
> hardly use particle system) you should give up the second
> method.
>
> 2009/8/4 Yaohua Xiong <xiongyaohua at gmail.com>:
>> Hi everyone
>>
>> I'm doing a traffic visualization project using blender
>> 2.5svn(details:
>> http://blenderartists.org/forum/showthread.php?t=161741&page=2) and
>> having some problem with rendering speed.
>>
>> I represent the vehicles in blender using two methods.
>>
>> 1. every vehicle is represented as an individual object(sharing the
>> same mesh) and use key frame move the vehilce
>> 2. vehicles are represented as a particle system, one particle for
>> each vehicle. The trajectory of particles are load in using external
>> cache file. every particle render as an object.
>>
>> The basic scene is the same for these two methods(2011 vehicles, 600
>> frame) but the rendering speed is very different. The rendering speed
>> for the first method is about 30 seconds/frame which I think quite
>> normal but the render speed for the second method is about 15
>> minutes/frame, it's 3000% slower!
>>
>> The real strange thing is that about 14 minutes of the 15 minutes is
>> spend on the "Filling octree" phase of render, but the number of
>> objects should be the same for both methods(2011 vehicles), what makes
>> the difference in render time and how this can be improved? Anyone got
>> an idea? Thanks in advance.
>>
>> --
>> Yaohua Xiong
>>
>> Traffic and Transportation Engineering College, Tongji Univ.
>> Cao An Road 4800#, Jia Ding District, Shanghai,  China
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>>
>
>
>
> --
> James Ruan
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>



-- 
Yaohua Xiong

Traffic and Transportation Engineering College, Tongji Univ.
Cao An Road 4800#, Jia Ding District, Shanghai,  China