Highway survey is a project with large data, large amount of calculation, which is a nightmare of road engineering design and survey personnel for computer united use to engineering calculations and data management. Using a computer's management and calculation of road surveying data is a very worthwhile investment, it will greatly improve road design speed, reduce road measurement and redundancy redundancy, reduce human errors, and so on.
1. "Road Engineering Survey CAD Information Management and Export System" solves the actual problems of road line type design:
1.1 Scientific management of measurement data, establish a database, and manage huge engineering measurement data.
Due to the low efficiency of traditional artificial handmade drawings, data find trouble, management is not easy. It's not difficult to imagine, what is easy to find some numerical values from hundreds of drawings.
The engineering data is managed, the vertical, horizontal, planar tables, and in the design of the database are established, and each table relationship data is standardized, and the third paradigm is compliant. Effectively reduce the redundancy of data, avoid insertion abnormalities, delete exceptions, and difficulties in modification.
For example, in the longitudinal section design database design, establish a "longitudinal section measurement data" table, "longitudinal data calculation results" table and "longitudinal ground line measurement data" table (as shown in Figure a), such database design meets BCNF ( Correcting the third paradigm), it will make longitudinal database design scientific, avoiding data redundancy, database insertion exception, difficulty modification.
Figure A relational database design
For a back surface example: In the longitudinal flop line design, if a "longitudinal data calculation result" table is established only, the data insertion abnormality occurs when only the actual measurement data of the longitudinal section is calculated. In the data calculation results, only the previous three records such as "slope point pile numbers", other, such as "outlet", etc. are empty, and cannot be inserted into the database. Insert anomalies.
1.2 Exact calculation of large engineering values. Remove engineering data by accessing the database, data calculation is performed.
Traditional numerical calculations, the road bridge engineers should continue to repeat the elements of the curve, the accuracy is not high,
Small precision and is not low.
With the "Road Engineering Survey CAD Information Management and Export System" for road line type numerical calculations, engineers do not need to perform manual calculations, just click on a button with the mouse, you can get calculation value and data report, and the time required is Second. However, such a quick calculation is of course a comprehensive program algorithm, eliminating the incorrect occurrence.
For example, in a planar line type design report design, it is necessary to consider the first and last piles of the curve elements and other pile elements (as shown in Figure B), we need to handle data table first and last records, respectively. Other sets of curve elements can be inserted into the database after calculating the specification formula.
Intersection
Intersection pile
Corner value
radius
Miter curve length
Cutting line
......
1
K0 000.000
2
K1 098.000
17 ° 02'12 "
1350.00
100.000
252.368
......
......
......
......
......
......
......
......
99
K2 876.000
10 ° 12'42 "
1000.02
120.000
150.050
......
100
K3 000.000
Figure B "Straight line, curve and corner" report
1.3 Get database data, communicate with AutoCAD, automatically generates longitudinal section, cross-section, etc.
Traditional handmade AutoCAD drawing to spend a lot of time, we can throw
Abandon this kind of painting drawing with a mouse?
"Road Engineering Survey CAD Information Management and Outcome System" Abandoned Manual AutoCAD drawing, which is responsible for drawing by the program, so that the Task of the Queau Engineer is only to use the index finger to press the mouse. Writing AutoCAD drawing road cross-section is one of the difficulties of the entire software development design. After the program draws the ground line and the road line, the intersection of the remaining slopes and the ground line is the difficult point in the difficult point. The following is a brief introduction to the computer algorithm of the ground line and the slope intersection (Figure C):
(1) First, declare the LX [I], LY [I]; RX [I], RY [i] is the left side of the ground line, the y coordinate, right measurement point X coordinate, Y coordinate. XO, YO is the original point O X coordinate and Y coordinate,
ROW is the number of points.
(2) Traverse the left side points x coordinate.
For (i = 1; i
{
IF (LX [i] greater than or equal to the left point coordinate BO) / / Find the target point
{
When the ground line slope does not exist, the intersection coordinate XD, YD of the ground line and the design line is present.
Because it is a line segment intersection rather than a straight intersection, it is necessary to judge the "true and false" intersection.
// Judgment is a true time
if the IF (is greater than or equal to the slope slope) // because the intersection obtained at this time will be wrong.
{
Provide painting wall;
}
Else
{
Painted line segments;
}
}
}
// If you can't find a true cross section on the left, the intersection must be connected to the first side point of the left and right sides.
According to the algorithm of the above, it is the intersection point, judge the true and false intersection, compare slope, drawing;
(3) Algorithm of the right drawing imitate the algorithm of the left picture.
Figure C Cross section seeking the slope intersection
2. The overall data flow of the "Road Engineering Survey CAD Information Management and Export System", as shown (Figure D):
The overall flow of the data can be discounted by a list of Figure D, first, establish or open the engineering database "Engineering Access Database", the software removes data from the database (arrow direction indicates data flow direction) for data processing (circle represents data processing), calculates the completion of processing After the data flows back to the "Engineering Access Database", then you can provide services such as report printing, engineering drawings.
This data process design method is easier to export the program block and the initial function module.
3. summary
The main difficulties development of road line CAD software is the database design and graphical calculation section. During the development of road CAD software development, graphical value calculations and their software tests should be given more time because of a considerable part of software, The mathematical calculation of road line CAD software is relatively complicated.
Figure D data flow chart
references:
Introduction to Sa Master, Wang Shan, Database System. Beijing: Higher Education Press, 2000.
[2] Schblebele. Programmer, advanced programmer software knowledge. Beijing: Tsinghua University Press, 1996
[3] SHASHI Shekhar and Sanjay Chawla, "Spatial Databases: a to
