Preparing Data to Import in Land Deskop or Civil3d
1. You have your data taken taken from a total station.
If you have data taken from a total station then you already have the coordinates ready and so obtain x,y,z data and description from your raw data and keep them in separate columns which will form your enzd column. Now for "p" column, simly drag 1,2,3... upto the end. You should end up as shown in the following diagram.
Then simply select all the required penzd columns hit ctrl+c and open a notepad and hit ctrl+v to copy the data into a notepad save as a text file.
Then you may proceed to another tutorial in this blog of how to insert those data:
2. You have your data taken from a theodolite.
Ok, no matter if you have your data taken manually from a theodolite. However a little more effort is required in excel. Type all you data into a excel sheet file and follow the following tutorial.
Download this excel file.
Here I’ll be explaining how to prepare x,y,z coordinates of the points of which you took your staff reading.
Land desktop or Civil3d creates contours from the 3d space coordinates that you provide. Those coordinates are nothing but the location of the points where you placed your staff. For land desktop or Civil3d whatever you use, to be able to draw contours, these coordinates should be entered in either [penzd] or [pnezd] or [nez] etc. format where
P = (point) the serial number of your points. Eg(1,2,3,4........)
E = (easting) the measure of how far is your current point towards east from the origin. This can also be called as x-coordinate of your coordinate system.
N = (Northing) the measure of how far is your current point towards north from the origin. This can also be called as x-coordinate of your coordinate system.
Z = (Elevation) the measure of elevation of the current point from the origin.
D = (Description) the description of the point you took reading of. Eg.. tree, building1, building2 sometimes abbreviated as t1, t2, b1, b2 for fast working.
The origin is not set independently rather you assume some arbitrary or known coordinate to a point and find the bearing of a line in your field to fix the position and direction of your coordinate system hence the origin is automatically produced and we pay no attention to where it is. The z-direction is always upward.
But the problem is how to create those [penzd] formats from the data in tachometrics sheets. Well this is done in excel rather than in land desktop. In excel you’ll need to fill 5 columns for [penzd]. I’ll upload the excel file where it is actually done.. how good isn’t it. Remember that always create your p-column at last(It doesn’t mean to make p as last column like enzdp, rather drag p column as last step of your penzd creation) because there may be some rows to omit for some mistaken points and if you do that after p-column is created, then your p-column won’t be serial, it will have some number missing, which can interpret less more points than the p-column shows. This may not create serious problem but doesn’t sound professional.
Now i’ll explain how to obtain the coordinates from the tachometric data sheets. I’ll be explaining the excel file that you need to download from the link I provided. This is just one of many ways to obtain the coordinates.
The above screenshot shows a tacheometric sheet exactly as I’ve provided you. The white background data columns represent the original tacheometric sheet whereas the blue background columns are what you need to work for. For this screenshot, the instrument is at station M30 and is sighted to M31. Our objective is to create the columns Q, S and T. Column Q represents the z-coordinate or elevation, S represent the x-coordinate or the easting, T represent the y-coordinate or the northing. Column R represent the description. I’ll discuss each column separately.
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Column C represents the height of the instrument (H.I).
To create column C, right click column D (which is initially column C) and insert a column. This inserted column will be now column C. Height of instrument is same for the station M30, so you may type 1.52 at cell c3 and drag down to copy the same 1.52 to all cells corresponding to M30 station.
Column D
Column D represents the forward bearing of the outer(Major or minor) traverse (M30-31). Yes, the excel sheet I’ve provided works only if the bearing of the line of sight (M30-M31) is forward. If you have back bearing of a line then convert it fore bearing using the relation.
Back Bearing = Fore Bearing (+-)180
This fore bearing data of major lines must have already been calculated before you start your detailing or once you close your major/minor traverse.
Since this data too remains true for all the points taken from M30 station, type 123.4935 in cell D3 and Drag and copy the same data in the column for M30 station. Note that I’ve converted (deg,min,sec) to (deg + min/60 + sec/3600) deg.
Column N
Column N represents the staff interval between top and bottom staff reading while detailing. As you click cell N3, you’ll see the formula in the formula bar as:
You may type the formula in the cell itself or click the cell and type in the formula bar.
Don’t forget the “=” before any formula in a cell in excel.
Once you’re done with N3 cell, drag down the cell for other lines to apply the same formula.
Column O
Column O represents the Horizontal distance between the theodolite and the staff. You can refer any survey book for information about this. However in the following excel sheet. The formula used is as shown in formula bar: (Double click and see cell O4)
It is nothing but the familiar formula K*s*(cos θ) 2
Where K = 100 (theodolite constant), s is the staff interval and N4 in our case and note that θ is the vertical angle. Make sure the vertical angle is as shown in the diagram below. Excel reads angles in radians so RADIANS convert the degree values to radians. Also the min and sec values in column I,J has been converted and added to degrees value in column H in the formula bar. Once you do for one cell, you just need to drag for others.
Column P
Column P represents the vertical distance MD as in diagram. As you can see in cell P4, the familiar formula K*s*(sin2θ)/2 is used there.
Where, the terminologies are same as before.
Column Q
Column Q represents the R.L or the z-coordinate of targeted point “D”. Remember you have already calculated the coordinates of your major/minor stations or traverse stations before you started detailing. Here those coordinates will be used. At cell Q3, you type the z-coordinate of M30. See the diagram above. To get the R.L of point D, you start from A which is known (Q3), then you goto B by adding the H.I (C4),then you go to M by adding the vertical distance(P4), then you finally land to point D by subtracting the mid staff reading(MD) (L4). Thus the formula is given as:
Note the dollar($) sign in Q4. Once you drag this formula below, you want all your c4, p4 and l4 to change their line as dragged , but not the q3, as you’ve sighted all the points from same M30 and its coordinate is fixed, hence to fix the value of Q3 as 499.112 over entire data taken from M30, you use the dollar sign. Now you are safe to drag and copy the formulas for next lines.
Column S
Column S represents the x-coordinate of the point you took the reading of. See the following diagram:
If you add the departure value of point D to the x-coodinate of station M30 which is already known, you’ll find the x-coordinate of point D and if you add the latitude to the y-coordinate of station M30, you’ll get the y-coordinate of point D. For other points like “D”, all you need is to drag the formula keeping $ sign to the coordinates of M30 as discussed above.
The formula for x-coordinate cell s4 (x-coordinate of M30+ L*sin(fwd. bearing +horizontal reading): =$S$3+O4*SIN(RADIANS(D4+(E4+F4/60+G4/3600))) , is self-explanatory. Similiarly, do for T column.
It is a better idea to merge the data of Column B and column R for better description. Merge for two beginning cells using either of the following two formulas and drag for the rest.
See sheet 2, cell f4
=CONCATENATE(L4,"_",M4)
You can also do
=(L4&”_”&M4)
Finally repeat the above process for all stations and copy the columns in new sheet
Erase whole row if you have a mistaken data for any point otherwise, you may endup with x-cor. of one point mismatching with y-cor. of other
Create the column entitled “P” i.e for points only at the end when you are sure that you now no need to erase the rows for any mistaken data so that you’ll have serial numbers under p column. You may then copy the penzd column in a notepad to use in land desktop. You can also create a csv file and paste the penzd columns in it.
In this way you create total station data from theodolite data to be used in land desktop or civil3d. Hope you found it useful. Well this is just the beginning, I’ll add more tutorials on land development and civil 3d later. Please do comment anything you like.
