Slide 1
Slide 1 text
Google Smartphone Decimeter Challenge
Pre/Post processing (PP)
Team: JTC
Private LB: 18th (2.841)
Reproducing baseline Main process
OSR data
from swift-nav
Calculation for
satellite position
(GPS only)
derived.csv
reproduced
baseline location
Reproduce baseline location by Weighted Least
Squares(WLS) used satellite position and corrected
pseudorange
・Weight of WLS are hand-tuned.
・Use only GPS/GALILEO/QZS
・Use scalculated satellite position(GPS only)
given
baseline location
(CV:5.29)
reproduced
baseline location v1
(CV:5.46)
① Blending
baseline location
GnssLog.txt
PP
1. Outlier Correction
2. Kalman Smoothing
3. Phone Mean
4. Remove Phone
5. Snap to Grid
6. Phone Mean
7. Stop Mean
lightGBM
PP
1. Kalman Smoothing
2. Snap to Grid
3. Stop Mean
4. Phone Mean
IMU data(acce, gyro, magn, rot)
Apply only
downtown area
reproduced
baseline location v2
(CV:5.21)
×0.5
×0.25
×0.25
③ Estimation for
location by IMU data
② Pre Processing ④ Post Processing
Weighted
average
Area classification
Copyright 2021 @kuto_bopro
Apply Kalman Smoothing to IMU
data and create lag/agg features
blend
location
(CV:4.95)
Outlier Correction
・Judge outlier based on 2σ and
movement speed > 45m/s
・Apply linear interpolation to outlier
by previous/next position
Remove Phone
・Remove data from a specific
smartphone and interpolate with
data from other smartphones.
Phone Mean
・
・Mean at the smart phone locations
in the same collection and epoch
(epochs were interpolated)
Snap to Grid
・snap prediction points to ground
truth grids
・apply downtown and difficult
area
Stop Mean
・predict car speed by lightGBM
・target: speedMps in ground truth
・apply mean for stop groups
Kalman Smoothing
・States:Lat/Lon and epoch
・Linear interpolation to keep epoch
width constant
lightGBM
car speed
grouping if speed < 0.95m/s for
2s gr1 gr2 gr3
mean mean mean
lag/agg feats
of location
openstreetmap
collections
more 5m
error points
highway
(open sky)
normal
downtown
(high multi path)
difficult area
(bridge etc...)
If the most common
attribute in the
"highway" column
is motorway
if mean degree >= 3
in road graph network
other
make buffer
(point to polygon)
ground truth grids
prediction points