Algorithm 1. Ttransition Point Detection.
Input:	Samples of WiFi RSSI
Output:	TP’s postion
Begin:	minimum distance equals infinite, nearest TP equals TP1
1:	for every TP fingerprint in database do
2:	while n < number of APs scanned do
3:	compare mac address of every AP with TP fingerprint
4:	if mac address is matched
5:	number of matched APs ++
6:	end if
7:	end while
8:	if number of matched APs > 3
9:	compute signal distance between samples and TP
10:	if distance < minimum distance
11:	update the minimum distance
12:	update nearest TP
13:	end if
14:	end if
15:	end for
16:	compare scene label of nearest TP to current scene
17:	if not matched
18:	return ture
19:	else return flase
20:	end if