[vtkusers] saving memory for XML writers?

Peter Schmitt pschmitt at gmail.com
Fri Jun 24 11:25:24 EDT 2005

It sounds like you open the file and load each datapoint into memory. 
Once the file has been completely read, you then create the grid and
store the data.  If that's the case, you may be able to improve your
performance by trying something along the lines of what I haev done:
(note: this is for a structuredgrid, for rectilinear grid you will
need to set the spacing arrays, obviously)
1.  Scan file to detemine dimensions of my grid
2.  Create grid, set dimensions
3.  Create point array, set dimensions
4.  Scan file, insert each point using its proper integer offset
	vtkPoints::InsertPoint (vtkIdType id, const float x[3])

This way vtk manages all of the memory for the grid, while you only
manage memory for one datapoint at a time.

Does that help?

On 6/24/05, tom fogal <tfogal at apollo.sr.unh.edu> wrote:
> Hi all, I've got a data file convertor that takes a proprietary file
> format and outputs VTK XML formats. For a typical 1.6gig input file, it
> unfortunately takes almost 6gigs of memory at its peak. I'd like to
> lower this significantly so we can use it on workstations.
> Just reading in the data file takes about 3gigs (as I would expect).
> Then, I build a giant RectilinearGrid, and pass that to an XML writer.
> I would like to know if I could build the RectilinearGrid piecemeal,
> that is, define a grid, write out the grid, delete grid data, write out
> one of the three scalar fields, delete it, write out another field,
> delete it, etc.. Basically I would like to keep the program overhead to
> sizeof(data) + sizeof(one_field_in(data)). Eventually I hope to fix the
> proprietary reader so it can read in a single field at a time...
> Does anyone know of a way I could do this, or have any other ideas to
> save memory?
> Thanks,
> -tom
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