About the accuracy of the zone detection

[iqfareez]

On a fine evening...

In my village at Temerloh, Pahang, while waiting for the Iftar time, I opened up this MPT app to set the new location to my current location here at the village:

So, the detected location is correct (Felda Sg Kemahal), so I select OK (PHG03). But then, I remembered my mom told me a long time ago that at kampung, we follow the time at Bentong (PHG04). So, to confirm, I opened up e-solat JAKIM portal. The portal has the ability to auto detect the user prayer time zones. 👍

The portal detected my location in PHG04, which as my mom said. Later, the azan berkumandang at the same time, which double triple confirmed the information.

I wonder

Was the location detection 'algorithm' being not accurate to determine the user location? If so, then I in a big trouble. 😓

My current detection method to determine the user location is by taking their coordinates and find the nearest places in the negeri. The nearest places will be the user's prayer time zones. I remembered that I've tested this method in the beginning in the development and the result was great.

The implementation

app_waktu_solat_malaysia/lib/location_utils/location_coordinate.dart

Lines 1566 to 1599 in 2c71e50

	/// Return nearest JAKIM code from the given coordinate and negeri.
	/// Pass administrative area as negeri.
	static String getJakimCodeNearby(
	double latitude, double longitude, String? negeri) {
	// when user is on perairan (kawasan air), negeri xdetect.
	if (negeri == null || negeri.isEmpty) {
	throw "Area not detected. Are you on a boat?";
	}
	List<int> tempIndex = [];
	double nearestDistance = 50000; //init distance to be 50 km
	late int nearestIndex;
	for (var i = 0; i < _locationCoordinate.length; i++) {
	if (_locationCoordinate[i].negeri == negeri) {
	// collect index of the same negeri
	tempIndex.add(i);
	}
	}
	for (var index in tempIndex) {
	// calculate distance each of indexes location with user location
	double distance = Geolocator.distanceBetween(latitude, longitude,
	_locationCoordinate[index].lat!, _locationCoordinate[index].lng!);
	// distance returned in meter
	if (distance.compareTo(nearestDistance) == -1) {
	// check the shortest distance
	nearestDistance = distance;
	nearestIndex = index;
	}
	}
	// return the nearby jakim code
	return _locationCoordinate[nearestIndex].zone;
	}

Edit: Above implementation will be moved to the server side. Check out https://waktusolat.iqfareez.com/api#tag/zones/operation/getZonesbyGps

Same 'algorithm', just processing will be handled by the server, so the problem isn't solved yet.

Resolution

• Let's conduct an experiment to see how different apps out there perform (cont'd below)

[iqfareez]

Comparison with other apps and websites

This experiment is conducted in Felda Sungai Kemahal (lat: 3.184531, lang: 102.278294), so, with our current knowledge, the prayer time zones should resolve to PHG04

Android apps

Apps	Screenshot	Result
Waktu Solat Malaysia	Screenshot_2023-04-20-16-10-06-066_com.murad.waktusolat.jpg	PHG03 ❌
Waktu Solat Malaysia - JAKIM	Screenshot_2023-04-20-16-19-57-675_amgstudio.waktusolatmalaysia.jpg	No auto location detection 〰️
mySolat	Screenshot_2023-04-20-16-24-47-655_my.gov.onegovappstore.mysolat.jpg	No auto location detection 〰️
Malaysia Prayer Times	Screenshot_2023-04-20-16-28-22-172_com.i906.mpt.jpg	Wrong time, so wrong location detected ❌
Muslim Pro	Screenshot_2023-04-20-16-41-56-480_com.bitsmedia.android.muslimpro.jpg	Wrong detection ❌
The Noor	Screenshot_2023-04-20-16-45-49-385_com.thenoor.app.jpg	Wrong detection (PHG03) ❌
Qalby App	Screenshot_2023-04-20-16-47-19-804_io.Qalby.app.jpg	Wrong detection (PHG03) ❌

Website

Website	Screenshot	Result
Portal e-Solat	as above	PHG04 ✅
Google Search	Screenshot_2023-04-20-16-51-03-231_com.android.chrome.jpg	?? ❌
WaktuSolat.my	Screenshot_2023-04-20-16-51-32-315_com.android.chrome.jpg	PHG03 ❌

API

API	Screenshot	Result
https://mpt.i906.my/api/prayer/3.184531,102.278294	image	JHR02 ❌🤨

Conclusion

None of the services above resolved to the correct prayer time zones except for official JAKIM website. Hmm.

[iqfareez]

The reference point for counting prayer times for all states in Malaysia

AzanPro

In the app, I'm using snapshot database from AzanPro API. The API seems to be down at the moment, however, the database is as follow:

https://github.com/mptwaktusolat/app_waktu_solat_malaysia/blob/a78f5086bdb74b97c496e530f1c71f1b342bd954/lib/location_utils/location_coordinate.dart

Map visualization:

JAKIM

"Titik rujukan hituangan waktu solat bagi seluruh negeri di Malaysia" from JAKIM Official.

https://www.e-solat.gov.my/index.php?siteId=24&pageId=43

PDF Receipt: Lampiran B.pdf

The file seems not up to date to recent changes in prayer zones ie the change of KTN03 -> KTN02, and the addition of NGS03. #160 #164

Map visualization tool

https://github.com/mptwaktusolat/jakim_zones_map

[iqfareez]

A thesis: Multiple Reference Point in Determining Zone-based Prayer Time in Selangor

#readthislater

http://www.pertanika.upm.edu.my/resources/files/Pertanika%20PAPERS/JSSH%20Vol.%2025%20(S)%20Feb.%202017/03%20JSSH(S)-0342-2016-4thProof.pdf

[iqfareez]

MPT Server's new API

A recent addition to the MPT-Server is the ability to determine user prayer time zone by their GPS coordinate. The method to achieve those is similar to what MPT app has implemented ie by checking the closest reference point in that negeri.

Example: https://mpt-server.vercel.app/api/zones/gps?lat=4.12&lang=102.5
Refer: https://waktusolat.iqfareez.com/api#tag/zones/operation/getZonesbyGps

MPT-Server doesn't rely on Google's geocoding service, but instead, utlizes GeoJson information from:

• https://data.humdata.org/dataset/geoboundaries-admin-boundaries-for-malaysia/resource/55b3dd6f-5786-4dce-b32f-5eca9bc8c16d [Source]

Other possible sources to look for:

• https://github.com/nullifye/malaysia.geojson (✅ best (I think), choose the District variant) [Screenshot]
• https://github.com/TindakMalaysia (They have the smallest division; up into the DUN level)
• https://gadm.org/download_country.html (Simplified GeoJSON: https://gist.github.com/angch/4bbbaa72ba0a9c95bfda951ca82b748f)

[iqfareez]

I'm currently working on added JAKIM Zone to a GeoJson in https://github.com/mptwaktusolat/malaysia.geojson

The added data can be visualized in Prayer Zone Visualization app.

[iqfareez]

Adding the JAKIM zones to all states in https://github.com/mptwaktusolat/malaysia.geojson is almost finished.

In the meantime, I have tried the geojson to retrieve result based on latitude and longitude. Preview deployment: https://mpt-server-ab9mhxi0m-iqfareez.vercel.app/

[iqfareez]

Issue fixed. App now will enquire the server for prayer time zone