The maximum RANSAC error for Sim3 alignment from reconstruction to pose prior is calculated from average position covariance：

But the member ransac_max_error in PosePriorBundleAdjusterOptions isn't taken into consideration.

I think the interface options should have higher priority. It may be modified like this:

if (num_covs > 0) { 
   ransac_options.max_error = prior_options_.ransac_max_error > 0. ? 
     prior_options_.ransac_max_error : (3. * (avg_cov / num_covs).cwiseSqrt()).norm(); 
 }