FHWS/IPIN2018
Archived
4
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

refactored sample impoverishment a littel

Browse Source
This commit is contained in:
toni
2018-05-24 12:12:24 +02:00
parent 525e1db540
commit d451d215cb
1 changed files with 7 additions and 4 deletions
Download Patch File Download Diff File Expand all files Collapse all files

11
tex/chapters/misc.tex
View File

@@ -102,10 +102,13 @@ For this, the state transition model is extended.
Compared to the resampling step, as used by the first method, the transition $p(\mStateVec_{t} \mid \mStateVec_{t-1}, \mObsVec_{t-1})$ enables us to use prior measurements, which is obviously necessary for all \docWIFI{} related calculations.
As described in chapter \ref{sec:transition}, our transition method only allows to sample particles at positions, that are actual feasible for a humans within a building e.g. no walking trough walls.
If a particle targets a position which is not walk-able e.g. behind a wall, we draw a new position within a very small, but reachable area around its current position.
%To prevent sample impoverishment we extend our transition method.
Instead of such a small are or even the complete building, as suggested in method one, we now define a sphere.
\todo{radius ist falsch! all connected triangles... warte aber noch aufs franks transition teil.}
The radius is given by $D_\text{KL} \cdot q(\mObsVec_t^{\mRssiVec_\text{wifi}})$ and particles are drawn uniformly on the mesh enclosed by the sphere.
%
%Instead of such a small area or even the complete building, as suggested in method one, we now define a sphere.
To prevent sample impoverishment we extend this transition method by making the reachable area depended upon $D_\text{KL}$ and the \docWIFI{} quality factor.
Particles are thus drawn uniformly on a sub-region of the mesh, given by a radius $ r_\text{sub} = D_\text{KL} \cdot q(\mObsVec_t^{\mRssiVec_\text{wifi}})$.
The sub-region consists of all walk-able and connected triangles within $r_\text{sub}$, including stairs and elevators.
%\todo{radius ist falsch! all connected triangles... warte aber noch aufs franks transition teil.}
%The radius is given by $D_\text{KL} \cdot q(\mObsVec_t^{\mRssiVec_\text{wifi}})$ and particles are drawn uniformly on the mesh enclosed by the sphere.
This allows to increase the diversity of particles by the means of \docWIFI{}, allowing to ignore any restrictions made by the system, as long as the difference between $\probGrid_{t, \text{wifi}}$ and the posterior is high.
The subsequent evaluation step of the particle filter then reweights the particles, so that only those in proper regions will survive the resampling.