[Rock-dev] MulitlevelLaserScan base type integration

[Sylvain Joyeux]

There is an option 4, which is having what information is currently stored in 
the "laser scan header" as common information in the new type, one 
std::vector<base::Angle> for angle for each scan and just have a 
std::vector<float> (or <double>, but given the data rate of e.g. the velodyne, 
<float> might really be a better idea ...) as data structure. One can then get 
accessors to extract LaserScan structures if needed.

I personally feel that the overhead of using base::LaserScan is way too big:
  - we get identical scan header information in each scan
  - we get as many std::vector (i.e. heap allocation and memcpy of *disjoint* 
memory) as there are scans

Remember that we are talking about ~20 000 scans per second in the case of the 
velodyne! To give a comparison, the hokuyo gives 40 scans per second.

Even if I am personally such a big fan of the idea, we could factor the common 
header laser scan information in a LaserScanBase class that is inherited by 
both the MultiLevel and the plain LaserScan

Outline of this proposal

struct TheNameOfTheNewDataStructure
{
   // Some data that I forget

   /** The time per-scan */
   std::vector<base::Time> scan_times;
   /** The angle-per-scan */
   std::vector<base::Angle> scan_angles;
    /** Start angle of a single scan */
   base::Angle start_angle;
   /** Angular step in a single scan */
   base::Angle step;
   /** Number of samples in a single scan */
   boost:uint32_t step_count;
  /** The data itself. The data for scan n is in 
    * samples[step_count * n] .. samples[step_count * (n+1)]
    */
  std::vector<float> samples;
};


-- 
 Dr. Ing. Sylvain Joyeux
 Space and Security Robotics
 
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