the method in this article is accurate only within 5 meters due to the limitation of the cell phone GPS receiver. professional surveyors use the "RTK GNSS" receiver but it might be too expensive for you. i saw some in ebay for $2,189. but even if you use a highly accurate method, your locations can't be used for official or permanent purposes unless you are a licensed surveyor.
more advanced mobile phones have more accurate GPS. example, in my experience, IPHONE 6s can be off 30 yards. iphone 11 is precise within 5 yards. i haven't tried the other iphones but i read online that iphone 14 can be precise within 1 yard.-
if you hire a licensed professional to survey your property, make sure to request that they give you the coordinates to all the mojons after the survey. this makes it easy to locate the mojons and detect if a mojon has been moved. what i do is after the survey, i pay extra to let the surveyor show me all the mojons. i take a photo of each mojon and ask the surveyor for the coordinate location. you can also open google maps and do a long press on the blue dot (your location) to display the coordinates. i then label the photo with the coordinates using the built in photo editor in my iphone. i then post the photo to a facebook album. i also message all family members or other owners of the property that the mojon locations are in an album in your facebook photos.
the method in this article can be used to ESTIMATE the boundary locations for the following purposes:
- locate a mojon if the property has already been surveyed.
- verify that the mojon is the correct location or hasn't been moved
- if the property is not yet surveyed:
- show prospective buyers the estimate boundaries for your property.
- show prospective buyers the estimate boundaries for your property.
- know where to plant your crops to ensure you are not encroaching.
- know where to put a temporary fence. but you need to inform your neighbors that your fence is not official because you just used a cell phone GPS which only has a 5-meter accuracy.
step 1: create a text file using notepad and give it a ".csv" extension.
step 2: copy paste the following sample to your .csv file and just modify it according to the technical description in your title, sketch map, or tie line date (which you can get from city hall). the 1st line is the heading. the 2nd line is the tie point. the tie point is located outside your property (sometimes very far) that many other properties use as reference. example, the tie line of the sample property below is 11,204 meters or 11 kilometers from the first mojon or corner of the property. the 3rd line is corner #1 in the technical description or sketch map. the 4th line is corner #2, and so on and so forth.
------------
NS,Deg,Min,EW,Distance
N,76,42,W,11204.62
N,8,40,E,47.07
N,6,29,E,30.79
N,69,25,E,122.36
N,55,59,E,53.9
S,43,40,E,38.6
S,44,33,W,74.95
S,61,39,W,120.32
S,72,41,W,39.77
------------------------
the reason i suggest you use a text file instead of excel is that sometimes, excel will use semi-colons (;) instead of a comma even if you specifically save it as a "comma-delimited csv file". lot plotter will not work if the csv file is not comma-delimited.
step 3: go to https://geoportal.gov.ph/gpapps/lotplotter and enter the province, municipality, and name of the tie point. note that tie point municipality can be different from the municipality where your property is located. example, in the above sample, the tie point is located in liloan while the property is located in guba, cebu city. so you should enter liloan and not guba. the tie point name is always mentioned in the technical description. example, the tie point name of the above sample is "liloan church tower". sometimes the tie name contains a BLLM or PRS acronym. the name may not exactly match any of the names in the drop down box of lot plotter so just choose the closest match.
step 4: choose the .csv file in lot plotter
step 5: click "upldate file" then click "done" then click "yes" to the "close polygon" prompt
step 6: click the globe icon in the upper right corner and choose "google map"
step 7: in my experience, the lot will always be very far from its correct location in the map. sometimes it will be in another barangay or municipality. so you need to maximize the "plot" sub-window and use trial and error to edit the Deg, Min and Distance values of the "TP to Corner 1" row until the property is in the correct location in google map. you need to already know where the boundaries will be in google map, which defeats the whole purpose of this article. this is not a problem if there is at least 1 boundary side mentioned in the technical description that is visible in google maps.
example, if the technical description says "bounded on the NE" by a road or river, then you just need to keep massaging the Deg, Min, and Distance of the "TP to Corner 1" row until the NE boundary of the lot aligns with the river or road.
otherwise, you will need to go to the location and ask the locals if anyone knows the location of at least 1 boundary. if one of the neighbors of the property fenced their property, then you are lucky because you can find the coordinates of each end of the fence then draw it in google maps (using the "my maps" tool). you can then use the compass tool in your smartphone to figure out which boundary side the fence is supposed to be. then you can massage the Deg, Min, and Distance of the "TP to Corner 1" row until the boundary is approximately located on the same location as the line you drew in google map.
step 8: click "export" and give it a name. example, guba-lot1. the extension of the saved file is ".kml".
step 9: open the .kml file in notepad. the coordinates are inside <LineString></LineString>. the first coordinate is the tie point. the 2nd coordinate is the first corner of the property. the last coordinate should be the same as the 2nd coordinate. this means the last corner is the 2nd to the last coordinate. you need to switch the longitude and latitude values before you copy paste to the google maps search box. example, if the coordinate in the .kml file is:
123.8480125043822,10.246977539124831
you copy paste the following to the google maps search box:
10.246977539124831, 123.8480125043822
--------------------
if you are selling a property, you can provide the potential buyers with the GPS coordinates and instructions on how to locate the mojons or corners. example:
you can show the boundaries of more than 1 property in 1 map by installing google earth pro (it's free) and going to File/Open to open the .kml files. you can open more than 1 .kml file.
(complete list of my knowledge bombs - https://ian-crystal.blogspot.com/2018/12/table-of-contents.html)
No comments:
Post a Comment