Hi,
I am looking for some help with this topic. I can physically locate the "NE Corner of Lot 1" in the field, and I have the N and E for this point.
Can I use my Topcon GPS to connect to this point and begin working from there, or do I need to account for the "Combined factor" in some way before proceeding?
Our plan is to build a pipeline in this area, and we would like to collect topographic points within our right-of-way. I want to make sure our workflow is set up correctly from the start.
Thank you, and I appreciate any guidance you can provide.
What datum are going to collect the data on?
Datum is NE Cor Lot 1.
N 6182989.37
E 657873.49
I think you need more guidance than I can help with. Your horizontal datum might be state plane it might be UTM it might be none at all and just a local system. You don't even mention a vertical datum nor a value for elevation. You will need some type of elevation datum even if it is just assumed. Also be sure not create an inclined plane when you do your topo. But if you think those coordinates are a datum you will need more help than I can provide in this forum in order not to screw something up.
This is why a license is required.
Can I use my Topcon GPS to connect to this point and begin working from there, or do I need to account for the "Combined factor" in some way before proceeding?
Native GPS measured data is always in grid. Topo and property lines are always measured in ground so yes, you need to enter a combined scale factor into the data collector software to convert the GPS-GRID data to GROUND data. Be careful. GRID = GROUND x CSF therefore GROUND = GRID x 1/CSF. As an example if your CSF is 0.9996 then you enter 1/0.9996 or 1.0004 as the CSF into your software.
I am concerned that you (the OP-original post writer) do not know what a datum is.
GNSS is good for horizontal +/- 0.03 (depends on the instrument, of course). Because of the math required to derive GNSS locations from the satellite vehicles in space, GNSS vertical error will always be about twice the horizontal error. That means you should not use GNSS for construction staking. GNSS is probably okay for as-built locating as long as the client is okay with your error.
No one cannot locate features outside a construction site unless you are working with or for a licensed surveyor. Licensed engineers can only supervise levelling and locating that is tied into a site control point or site benchmark that has been set by a licensed surveyor. (Because of continental drift, you can't just grab coords off some map and assume they still hold.) Contractors cannot stake construction points and cannot locate site features without being directed by the site's licensed engineer or licensed surveyor.
These restrictions are not just surveyors claiming territory. These restrictions are to protect the public welfare.
I can't quite make out the information on the shown plat. I think you're in BC and the Datum is UTM in Zone 10 which makes sense for BC.
They show a combined scale factor of .99??94, I'm not sure about the third and fourth numbers, I think the fourth one is a 7.
They show a rotation to Astro north of 2plus degrees so you're a distance from the Central Meridian.
To get on this system you can calculate coordinates from the given one and occupy a point that has a calculated coordinate, create a file in your GPS using UTM zone 10 as the datum, enter the coordinate of the occupied point, start the base and try and check-in to other given points on the plat. If you check then you're as good to go as you can be and you know this plat is on UTM coordinates and the ellipsoid. If you don't check but the inverse between the points is very close for bearing and short for distance apply the combined factor and see if that corrects the misclosure. If it does then you know the combined factor was applied to the plat drawing putting it on the surface. I don't know about Topcon, but in Trimble there is a site setting that allows you to apply the scale factor around the base point which will fix that issue. As a very last resort you can calibrate to your calculated coordinates. As far as elevations go, I would use Geoid 18 for that, If none of this makes sense, you have a ways to go to use GPS for staking a pipeline or anything else.
UTM is a projection, not a datum.
Canada probably has their latest realization of NAD83(xxxx) for horizontal datum and CGVD2013 or later for vertical. These determine chere you are, and UTM or other projecton determine how you quantify it.
In the US your location can be tied to the same datum and expressed in lat-lon, UTM, SPC, or regional low distortion projections.
UTM is a projection, not a datum.
Canada probably has their latest realization of NAD83(xxxx) for horizontal datum and CGVD2013 or later for vertical. These determine chere you are, and UTM or other projecton determine how you quantify it.
In the US your location can be tied to the same datum and expressed in lat-lon, UTM, SPC, or regional low distortion projections.
UTM is listed in the Datum reference on the plat, I very much doubt that there is a way to use ITRF or other Datums with the OP's knowledge of the DC. I'm assuming that UTMzone10 is an easy entry from the pull down menu.
@landbutcher464mhz native GNSS observations are geodetic observations: latitude, longitude, and ellipsoid height. Your field computer will show you positions based on the display setting chosen.