hi guys and welcome back to SITENG in today's video i'm going to tell you about the global
grid and the local grid the differences and i'm going to describe you what it's all about and
why we say global grid and how to use the local grid as well i'm going to start from the british
national grid here and i'm going to explain you what it's all about with all these squares
and then later guys i'm going to jump into the cut drawing i'm going to create a local grid
here and i'm going to explain you how to do it step by step and before we go guys please don't
forget to subscribe to my channel leave the thumbs up if you like it leave the comments
if you got any questions and don't forget to follow my linkedin page as well so let's go
so guys i know everyone asking about the local grid or local local global so i decided i'm gonna
do actually probably two videos about this as i want you actually to know what what we mean by
saying global grid and local grid so first of all i'm going to start from the global grid and i'm
going to try to explain it the most engineering way at in terms of like site engineering and
civil engineering as this is obviously a geodesy and all surveying uh and all these guys probably
got more knowledge about it and they as well need more knowledge about it but for us engineers who
wants to work in construction we need actually the little knowledge but to get the understanding of
what's going on and not to be just blind and trying marking and all the stuff so i decided
i'm going to start from the global grid and in this case guys uh it's not really the global grid
what we're using here it's a british national grid and you can have a look i opened actually
wikipedia i leave the links here so you can read through it anyway i'm not going to be spending too
much time on it as uh as i said you can read through it but what i want to show you i want
to focus a little bit about this map here and the system use for the coordinates but before
i say a little bit more about it i just show you the geoid which is the which is the model of the
earth it's it's based on the ellipsoid so based on that shape obviously all the systems all the
grid systems are created so this is another one you can just have a look on the wikipedia
and have a look yourself read about it a little bit how the model was created
and what is why why this is important to know there is something like this and based on this
shape everything is calculated later and also i want to show you this this is actually the 1984
geoe models so this is world geodetic system is wgs84 you've probably seen it i think it's even
in the edm you can you can have a look at this it's probably show this basic coordinates so
this is all obviously the cartesian coordinate system but then applied to this model and then
that's what we're actually using on site for the setting out so i'm gonna go back to that nice
uh map here and that division here and i'm gonna explain a little bit more about it but uh before i
jump to this i want to open the cut and i tell you a little bit what we're doing here as engineers as
we are making our life always easy and easy and the way we're doing this is always approximation
interpolation and the making error so small that we can actually omit it so that's exactly
what's happening here as well uh in terms of setting out i quickly jump here on autocad guys
i mean i'm going to show you something if i create ellipsoid let's say guys here
let's say it doesn't really matter how it's going to be looking obviously let's say not going to be
looking more like earth i think this can show you the easiest way so so you're going to so
you're going to understand uh how are you working and that's what i said about the approximation
all the interpolation and all the stuff to make easy for us engineers as remember guys engineers
want to make life easy for themselves so if i'm going to take the line let's say
and i'm going to make it tangent to this you can see that all this let's say even the arc wherever
you can see the shape of the ellipsoid but once i'm gonna start zooming in guys
and getting closer and closer and closer obviously there is a one point tangent point but as you can
see now the closer i'm getting to this the more flat it is and if you zoom it enough our line
gonna be actually covering that part of the of the ellipsoid of of that arc so you can see guys
the closer we are getting to this the more flat the surface it is and the same story is with the
earth and the same story goes for the coordinate system as obviously guys while we're working on
site we're using the coordinates for us that area that that few hundred meters we work in
is actually flat and we treat it as flat when we add in the meters and meters and centimeters
wherever we're not thinking about the curve of the earth and all that stuff so the closer you are
you're actually the closer to the flat surface i'm gonna go back to that map here and uh you can see
this squares let's say in this case i think that's that's that's the best one
uh each of these squares guy is 100 kilometers and as you can see here let's say that's actually
showing this is a good case in london here it says royal observatory greenwich so that's
again what i said uh it's it's it's not the global it's not the global grid this is the
the british grid and we call it global obviously wherever you're going to be on site someone says
oh in global or in local but the one thing you need to remember guys once i'm talking about this
if you're using the robotic edm uh if if if using ts15 or ts16 on topcon robotic where you can
actually upload the drawings you're going to be working in our global system is this is no point
to creating a local grid for your job but anyway i'm going to tell you about a local grid as well
so we're going back here each of this square is 100 kilometers and some of you guys maybe work in
london here you know there was a you had probably easting 50 to something and northing 18 i uh on
the last job i hit 19. so uh the reason for it guys is look 100 kilometers so let's say one two
three four five so that's the reason for it's 5 52 or whatever so this is 500 kilometers so that's
the reason why you're working in global grid you got 500 kilometers so we got all these digits then
dot and we got the millimeters obviously we work into the millimeters we want to get it exactly
as possible once we set it out on site but all these digits all these meters are exactly this
so 500 kilometers gonna be your 500 000 meters and that that's why the numbers are so big and
once you're gonna get it local you're gonna make it probably smaller so we're gonna be easier to
type in especially when using the ts06 and the same goes for northing obviously so we got 100
here 200 here so we got 18 here we somewhere here let's say uh in terms of london and actually uh
just showing the greenish observatory here and uh if you want to know about
what these letters mean so you can actually go to wikipedia we don't really care about this as
we working with the digit so obviously as you can see here the tq that's that stands for this
particular square which is then divided uh to even more square and this square is also divided to the
more squares guys so that's exactly what i showed you on that cut drawing that curve the smaller it
gets the more flat it is and then we can work in the area treating it as a flat surface i
really recommend you to go through this links open this read through it and if you got any questions
obviously guys leave the comments and i'm gonna explain a little bit more if you need it but i
think from our engineering point of view that's all you need to know guys that there is some geoe
model created and actually our global grid guys that's that's the british geoit system here and
that's the coordinates we're using working here in uk and obviously if you're going to be working
somewhere else in other country i don't know maybe abu dhabi or wherever you're going to be working
you're going to you're going to have a different system so don't be surprised if you see completely
different numbers where you're going to be putting instinct and northing so guys i'm going to try to
tell you a little bit about the local grid as well so let's say we're working in one of these
squares here and once we get closer and closer and closer and closer obviously somewhere there
that that our building gonna be somewhere there in that square and i'm gonna open drawing now quickly
and uh tell you a little bit about it so guys i got a drawing here now it's one of the blogs
on which i cover in my site videos if you remember but this is the higher level here and let's say we
want to create a local grid obviously guys while we're using the robotic total station
like ts60 and ts 15 top console whatever we're going to be uploading information drawings to our
controller or to our tablet and then we're going to be doing setting up so there is no reason
for creating a local grid and working with it but when we're working with the so-called
two-man stations like tso6 typically the very good thing will be and that might be actually the very
first thing we're going to be doing on site with with the old grid system we're going to create
a local grid i'm going to use this drawing here and my starting point for my grid is going to be
this one the crossing of gridlines c1 and cn and that gonna be my corner of my building actually
so guys as i said this is in global just gonna show you quickly here id so this grid line was uh
51 something and 18 something which coming back to our squares from uh where we got these numbers
so this is global grid guys and this point is actually very important that's that's going to be
my point i'm going to be referencing my local grid 2 and based on this i'm going to change everything
and obviously our our control points as well so when we're going to do the resection we're going
to be actually setting our edm in the local system but this i'm gonna keep to the next video guys
when i'm gonna tell a little bit more about it i'm gonna show you the spreadsheet you can use
and also i'm gonna do maybe another drawing uh just to clarify everything
so guys for this uh for changing this into global guys i'm gonna use the ucs command here
and uh so that's the ucs and to make it square to the building our new grid make it parallel i just
press here and i'm gonna go with the grid line so i'm going to find the intersection here to be sure
they're not going to be any error so that's the intersection here of these grid lines and
intersection of these grid lines here and for now guys this point here is my new zero zero point uh
but i'm going to move it in a minute anyway so you can have a look here this is zero zero now and uh
this grid line here uh if i press the id and that grid line gonna be zero zero and eight four three
five so what i want to do guys now obviously i don't want my grid line to start at zero zero
uh i'm going to use let's say 4000 for easting and 2000 for norfolk so i'm going to take all this
drawing now and i'm going to just move it to the point here this drawing is in millimeters guys so
obviously i have to use it i'll take this point from here and i'm going to use 4 000 that is
millimeters and 2000 that gonna be our northing and i'm going to press enter double click the roll
so i'm going to get to here now we're going to double check now if this is correct now if i move
it correctly id 4000 2000 so that's exactly what i wanted and that should be 2008 let's have a look
if this is the case so that's easting 4000 and and northing 2008 435 so yeah this is in millimeters
guys so in the next video i'm going to show you that spreadsheet i'm going to tell you a little
bit more about the local grid and i'm going to do next drawing in meters so they're going to be all
clear so guys as i said this is my 4000 so i can actually call it you're going to see this on some
jobs people typically they got the drawings with with a with the grid lines marked so that's our
four thousand and zero zero millimeters and uh that's the easting and i'm gonna put the number
here on the northing which is our 2000 in this case guys and obviously guys uh please wait for
for the next video where i'm going to explain a little bit more about it and if you got any
questions just leave them here so i can maybe even answer while i'm gonna be doing that video but
that's how it works guys and this is four thousand here two thousand and if you look if you're gonna
be looking for the gridline c2 let's say that's gonna be our four thousand plus eight four three
five so this is me millimeters guys so our grid line c2 gonna be four thousand eight meters point
four three five millimeters and from this number obviously wherever we're gonna be setting here
so this way you're gonna be adding and this way you're going to be distracting guys but once you
got the cut drawing set like this obviously you can use id point and whatever id you're going
to have here not going to be in your local grid and you can just type it in to your instrument or
you can just copy from the cat drawing and upload it into your ts06 and once you got it here press
that going to be 4009 335 and 203.652 millimeters that's this corner in the new local grid which we
just set so guys uh i think that's the that's the easiest easiest way to create a local grid and
obviously later you can align your new drawings and all the stuff i'm going to show you in the
next video i don't want to make it video too long i just uh i just want to make sure you understand
the old big picture how it's all created how the grid is created how then becoming the
smaller fragments uh make it more flat for us so we're actually working only on it in that curve
as the error is so small it's it's obviously near to zero so it's for us is zero and we're
working in the flat and then we're creating we can getting closer creating for our blog we can create
a local grid and then work with it so guys i think that would be all into this video i think uh
i covered a global so-called global grid for us that our british grid here for the uk and then
the local grid i think that shows you how it works guys how you can change it yourself obviously you
can move it to whatever point you want and then in the next video guys i'm going to show you the
transformation so we can actually gonna be using our control station and all the points so we can
set in that local grid and then using this drawing which is changed now to the local we're gonna be
doing our setting out so thank you again for watching guys if you like it guys don't forget
to leave a thumbs up leave some comments guys below this is helping to grow this channel and
making more people watching this and get more knowledge about these things and please don't
forget to subscribe to this channel and thank you again for watching guys and see you next time