# Boost :

Subject: Re: [boost] [gsoc17]The implement of Programming competency test From Ruoyun Jing
From: Vissarion Fisikopoulos (fisikop_at_[hidden])
Date: 2017-03-28 10:42:50

Hi Ruoyun,

it seems that you are making a big effort understanding the tools of
the area. Your ideas are more than
enough to form a proposal. you should concentrate to make them more
clear. Try to keep it simple and
clear. Also regarding you English, I am not a native speaker to give
try to make short sentences with simple English, in some parts it is
not very easy to understand what
you want to say, but in general I think you are passing the message.

Looking forward to see your draft proposal.

Best,
Vissarion.

On 27 March 2017 at 14:39, Ruoyun Jing <jingry0321_at_[hidden]> wrote:
>
> 2017-03-25 0:46 GMT+08:00 Ruoyun Jing <jingry0321_at_[hidden]>:
>>
>>
>> During these days I discussed the ideas of project 1 and begin to write my
>> proposal. Here are what I learn about these project.
>>
>> 1.For the approach of compute the 3D cartesian distances first and if
>> these numbers are not "far enough" then fall back to expensive geographic
>> distance calculation otherwise return the result by comparing those numbers
>> obtained by less expensive cartesian compuation.
>>
>> The main problems is declare the "far enough". To figure out this problem,
>> I would implement the method, test the result between function
>> compare_distance and this method, then adjust parameter to limit deviation
>> in an acceptable range(maybe it would be 1e-6 correapongs, the accurate
>> value should be discussed by specific condition)
>>
>>
>> 2.For the approach of perform a local spheroid approximation and return
>> the 2D distance.
>>
>> The main problem is to test the acceptable range of using spheroid
>> approximation. The solution is same as answer above.
>>
>>
>> 3.For the approach of getting 2 intersections of plane (which would be
>> ellipse) with the help given points and compute the respective distances
>> using those ellipses.
>>
>> In my understand of these approach, it means we need to get cross-section
>> through the center of ellipsoid and the geodesic segments. But I am not sure
>> that the geodesic segments of two points whether can get a cross-section
>> through the center of ellipsoid, and whether the cross-section is ellipse
>> that we can calculate the sectorial area easy to compare. After check out
>> the geodesic knowledge from differential geometry for a long time. I got
>> some prove, but I think it isn't very reliable.
>>
>>
>> 4.I have an reliable approach is that we could use the algorithms in "map
>> projection" just like Lambert Conformal Conic, Gaussâ€“KrÃ¼ger projection,
>> Mercator projection...etc,
>>
>> Those projections make the point on 3D to 2D with reliable functions,
>> although most of these projections use longitude and latitude, we could
>> transform our cartisian coordinate into Spherical coordinate then transform
>> them into longitude and latitude then use the projection to approximately
>> calculate.
>>
> I read more about projection and we could use Local Cartesian Projection,
> one of the equidistant projection, which can provide ellipse and spheroid
> model.
>
>>
>>
>> All of above is what I discussed during these days, Could you please
>> provide me some advise about them so I can strenthen my proposal?And if
>> there has any problems about my poor English description please tell me, I
>> will try my best to explain more clearly:)
>>
>>
>> Looking forward from you.:)
>>
>> Ruoyun
>> --
>> Northwest University of China
>> Software Engineering
>> jingry0321_at_[hidden]
>
>
>
>
> --
> Northwest University of China
> Software Engineering
> jingry0321_at_[hidden]