Region Aliasing Error

[Shreya Chakraborty]

While working on a problem, I am getting the following error:

F0725 00:27:23.114425 10218 problem_impl.cc:77] Check failed: !RegionsAlias(existing_block, existing_block_size, new_block, new_block_size) Aliasing detected between existing parameter block at memory location 0x252c580 and has size 4 with new parameter block that has memory address 0x252c588 and would have size 4.
*** Check failure stack trace: ***
    @     0x7fcf63906daa  (unknown)
    @     0x7fcf63906ce4  (unknown)
    @     0x7fcf639066e6  (unknown)
    @     0x7fcf63909687  (unknown)
    @           0x7bc3e9  ceres::internal::(anonymous namespace)::CheckForNoAliasing()
    @           0x7befdf  ceres::internal::ProblemImpl::InternalAddParameterBlock()
    @           0x7bfac5  ceres::internal::ProblemImpl::AddResidualBlock()
    @           0x7c0674  ceres::internal::ProblemImpl::AddResidualBlock()
    @           0x481b01  DfUSMC::evaluateMesh()
    @           0x474c03  main
    @     0x7fcf62735f45  (unknown)
    @           0x475750  (unknown)
    @              (nil)  (unknown)


I am unable to understand the source of the error. Here is my simple code for initializing the residual block.

for(int i=0; i<num_vertex; i++)
    {
          
        ceres::CostFunction* cost_function = CostFunctor::Create(indices_conn[i].size());
       
        problem.AddResidualBlock(cost_function, NULL, new_z + (i), other_xyz + (i*4) );

    }

Here, other_xyz and new_z is declared as:
double *new_z= new double[num_vertex];
double *other_xyz=new double[4 * num_vertex];

Can you tell me where the aliasing might be occurring?

[Sameer Agarwal]

what sized parameter blocks is the CostFunction expecting? its likely that it has the wrong sized parameter blocks specified.

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[Shreya Chakraborty]

I just checked. I had accidentally put the size of the residuals later. It was such a silly mistake, sorry for bothering you!

[Sameer Agarwal]

your parameter blocks are swapped the cost function expects 4, 1 and you are adding as if they are 1,4.

On Mon, Jul 24, 2017 at 12:33 PM Shreya Chakraborty <shreya...@gmail.com> wrote:

The parameter blocks are of of size 1 and size 4 respectively.
Declaration within Create:

static ceres::CostFunction* Create(const int num_indices) {

        return (new ceres::AutoDiffCostFunction<CostFunctor, 1, 4, 1>(new CostFunctor(num_indices)));

    }




On Tuesday, July 25, 2017 at 12:47:54 AM UTC+5:30, Sameer Agarwal wrote:

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[Shreya Chakraborty]

Yes, I realized it!