linear_solver_type

[Jianxiong Xiao]

I am working on a huge bundle adjustment problem. Thanks to Ceres, my life is much easier now. But I have some problems to scale it up even larger. 

If I set options.linear_solver_type = ceres::DENSE_SCHUR;, everything works perfectly.

But, if I set options.linear_solver_type = ceres::SPARSE_NORMAL_CHOLESKY, it produces the following errors.

To scale it up, I want to user the sparse solver. Otherwise, I guess that there is simply not enough RAM to run.

Does anyone have any advice on what to do now? Any tips will be highly appreciated. Thanks!

I use all default parameters for options except options.ordering_type = ceres::SCHUR;

W0918 20:55:08.032258  6827 suitesparse.cc:297] Cholmod warning: matrix not positive definite.

W0918 20:55:08.033293  6827 levenberg_marquardt_strategy.cc:109] Linear solver failure. Failed to compute a finite step.

Best,

Jianxiong.

[Sameer Agarwal]

Hi,
Can you do a dump with -logtostderr -v=2 . Also how big is your problem? Sameer

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[Jianxiong Xiao]

Thanks, Sameer!

> Can you do a dump with -logtostderr -v=2 .

I will do that and report back. My code is in Matlab and I use Ceres
as MEX in matlab. So I may have to try and figure out how to set this
flag.

>Also how big is your problem?

I have about 20,000 images each of which has about 500 SIFT key-points.

Best,
Jianxiong.

[Keir Mierle]

On Fri, Sep 21, 2012 at 5:14 PM, Jianxiong Xiao <jx...@csail.mit.edu> wrote:

Thanks, Sameer!

> Can you do a dump with -logtostderr -v=2 .

I will do that and report back. My code is in Matlab and I use Ceres
as MEX in matlab. So I may have to try and figure out how to set this
flag.

Interesting; where did you find a MEX wrapper? If you compiled Ceres with gflags support, you should be able to do:

#include "gflags/gflags.h"

DECLARE_int32(v);

...

FLAGS_v = 2;

or something similar.

 

>Also how big is your problem?

I have about 20,000 images each of which has about 500 SIFT key-points.

Wow, you'll need a bunch of memory for this!

Keir

[Jianxiong Xiao]

> Interesting; where did you find a MEX wrapper?

I wrote one for myself. I can share my code if you guys decide to have
a mex wrapper.

> If you compiled Ceres with gflags support, you should be able to do:

Thanks for the tip. I will try that.

> Wow, you'll need a bunch of memory for this!

My machine has 196GB memory. So I want to try to make it work.

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Best,
Jianxiong