| James Wong | Saturday, August 09, 2003 - 11:14 pm
The largest pool indicated at location 4 of your route indicated altitude of 190m should be 220m.
We went there today and could not find that pool at 190m. After lunch we moved up and found that pool at 220m. Our altitude was measured by GPS Model Garmin GPSIII. If my GPS was correct, your altitude for the rest locations were also not correct. |
| Lawman | Sunday, August 10, 2003 - 01:33 pm
Thank you. You may be right. The day we went there was cloudy with isolated shower which could affect the accuracy of our air-pressure type altitude meter. |
| Ron | Monday, August 11, 2003 - 11:49 am
Hi James,
Do you notice how your GPS report the altitude in other locations, such as hill tops with known height on maps? While land surveyors do use GPS for accurate reading and making our maps, many portable/hiking GPS models do have significant difference in the altitude reading as compared with our maps (the horizontal coordinates have no problem). My friend use a eTrex GPS and we never believe in its altitude reading. We notice that our barometer/ altimeter watch do have a better accuracy if we calibrate correctly at the start of the hike. |
| James Wong | Sunday, September 07, 2003 - 07:20 pm
Compare to HK map, my GPS reading is within 5m error at most hill top. However the error may be increased at stream where reception is always not as good as hill top. May need to compare again next time in stream when limited satellites are logged on (min 4 for alititude measurement). |