At the request of an alumnus who missed the class, I answer a question regarding the construction of polygonal lines in AutoCAD.
In this case we have a table, in the first column we have the stations, in the second the distances in meters and the third column contains the bearings.
Well, we will proceed to build the traverse, then we will verify the closing error and finally we will talk about the box of bearings.
1 Enter the bearings and distances manually.
The nomenclature that AtuoCAD accepts to show the data is known as polar coordinate (distance and course) in the following format:
@ distance <N / S degree d minutes ' the 2nd »E / W
The values @, d, ', »are only nomenclatures that the system requires to interpret the data
The N / S and E / W values are for choosing one of each, such as Northeast, you would choose N and E
Bold values are numeric data, the latter can carry decimal values.
If a value is zero it can be ignored
For the case, sequentially it would be of the following form:
- Line command
- Click on a point on the screen
- @11.21<S68D (enter)
- ...... enter the rest until the last station
- @57.34<N17dE (enter)
Although this nomenclature is somewhat archaic, because now there are macros and special applications to import the data, the Autocad veterans prefer to enter them because of the acquired practice; so I ask for tolerance, for insisting on understanding the initial concepts, then taking shortcuts. Also, if they knew how we learned this before the 2.0 website existed, they would understand why I prefer to share it rather than keep it in the trunk of memories :).
2 Enter courses and distances from Excel.
Previously we had seen how Enter UTM coordinates from Excel, only using the function "concatenate", because this time we will try to use that same function, with the intention that it will help us to construct the picture of directions and distances.
The disadvantage of entering the data on foot in the AutoCAD command bar is to make a mistake in a value, and then verify if they were entered correctly. In this case we will see how to use Excel to enter them and then extract them to AutoCAD, without using lisp, or macros.
This is an Excel table in which the data has been concatenated.
So if you enter the data in the columns marked in yellow, the process is simplified to:
- Line command
- Click on a pounto of the screen
- Select the excel area marked in green, copy (ctrl + c)
- Click on the command bar, paste (ctrl + v)
Ready, your polygon is built, if it is left open or some data seems strange, just check the values entered in the table excel, and do the procedure again without typing each value.
3. Verify closing error
In this case, to verify the closing error, we do the following:
Approach the point where we started, and measure the opening distance between the end point and the starting point. This is done with the "dist" command, if in this case 0.20 generates me
Now we divide the perimeter (sum of all distances) between that differential. (1,017.66 / 0.20) = 5,088
Which means that the precision is one in 5,000, that is one meter of error for each 5,000 linear meters. To know if it is acceptable you must know the acceptable parameters in your locality, generally for urban walk up 1 in 3,000 and for rural above 1 in 1,000.
If the closing error is within the parameters, we must obbligate the polygon closure in one of the lines, preferably in the one of smaller length, this to make sure that the angular error we are applying in the side that will less affect the area of the Polygon ... then we have to correct that course we have adjusted.
If the closing error is outside the parameters, verify that you have entered the data correctly, then verify the field record and finally ... send the surveyor back to the land
4 Build the box of bearings and distances
Well this topic we will see in another post when we do it with Civilcad, since in this case we have used Excel to enter the points, so to make matters worse, we just copy and paste the table that is to the right of the archive, Which has concatenated data to just do copy + paste.
It is preferable to use special paste, to choose between autocad entities, ole object, image or block.
Greetings and until next time.
Now comes the educational part of the 2.0 Web, which macros or applications use to enter a table like this?