Drawing preprocessing

13.1 Drawing preprocessing

13.1.1 Drawing Preprocessing Guide

Before importing CAD drawings into SU, pre-processing should be carried out to meet usage requirements.

The "Drawings Pretreatment Guide" is a fast processing tool whcih is provided to customers based on pre-processing requirements, integrating the relevant functions mentioned above. It is recommended to use it.

13.1.1.1 Preparation for drawing preprocessing

After using the "Drawings Pretreatment Guide" function, a prompt will pop up automatically to confirm that the preparation work before using the tool. Then, a pop-up box will appear to select if to automatically execute the "PURGE" command to clean up the drawing (this step mainly cleans up empty layers and blocks in the drawing).

The main operating steps are as follows:

13.1.1.2 Step 1: Global process

This step will automatically convert the 2D and 3D polylines in the drawing into polylines, adjust the linetype of all polylines to "Continuous", lineweight and line thickness to 0, and clean up interfering elements far from the main drawing.

User can click the "Handle" button to automatically process the items in the list. If there are any interference layers that are far away from the main image and useless, a pop-up box will appear. Simply check the area identified as interference elements and click "Clean". After processing is complete, the software will pop up a "Process completed" dialog box.

User can click "Next" to complete the current step and enter the next processing interface.

13.1.1.3 Step 2: Contour lines and elevation points

If the contour lines and elevation point layers are not named "DGX" and "GCD" and need to be manually selected, the software will automatically process abnormal points or elevations in the contour lines and elevation point layers. When abnormal points or elevations are detected, a dialog box will prompt whether to delete them.

13.1.1.4 Step 3: Red line and generate scope

This step requires manual selection of the red line range and the generated range layer. If the generated range does not need to be processed, users can choose "No treatment".

In this step, both the red line range and the generated range will be processed into a closed polyline range. For unclosed polylines, the software will automatically use "Closepoly" command to process polyline closure. After processing is completed, the "Checkpoly" command will be automatically used to check the closure of the red line range layer. After passing the check, the red line range will be automatically merged, and then the "Checkpoly" command will be automatically called again to check the closure of the merged "Candela-Region-ValidArea" and "Candela-Region-InvalidArea" layers. After passing the check, click "Next" to complete the current step and enter the next processing interface.

13.1.1.5 Step 4: Road

In this step, the software first detects whether the polylines in the selected road layer need to be simpified, and removes duplicates and self intersections from the simpified polylines.

Next, the software will create two layers: "Candela-Region-Road" and "Candela-Center-Road". It is necessary to manually distinguish between the double line roads and single line roads in the original road layer, place them in their respective layers, and manually process the closure of intersections and end intersections of the double line roads. After completing each step, users need to manually check the box in "Status" next to "Untreated" to switch to the "Completed" state.

After that, the software will automatically call the "Checkpoly" command, and users need to manually check again whether the polylines in the "Candela-Region-Road" layer are closed. If there is a circular road (described as "included by other polylines"), a dialog box will pop up to input the "Break space".

13.1.1.6 Step 5: River system

The processing method is the same as "Step 4: Road".

13.1.1.7 Step 6: Independent features

In this step, it is necessary to manually select the independent feature layer. The "PL" command needs to be used to circle the independent features in the set, and all range lines need to be placed in the "Candela-Region-Independent Features" layer. The check-box next to "Processing" needs to be manually checked to switch to the "Completed" state. After processing is completed, the "Checkpoly" command will be automatically called, and it is necessary to manually check whether the polylines in the "Candela-Region-Independent Features" layer are closed again.

The software can automatically draw a closed range around scattered blocks in independent features, with shapes of circles or squares and customizable sizes.

13.1.1.8 Step 7: Residential areas

In this step, it is necessary to manually outline the exterior of the building and place all boundary lines in the "Candela-Region-Residential Area" layer. users need to manually check the check-box next to "Processing" and switch to the "Completed" state. After processing is completed, the "Checkpoly" command will be automatically called, and users need to manually check whether the polylines in the "Candela-Region-Residential Area" layer are closed.

13.1.1.9 Step 8: Features

In this step, the software only checks whether the selected terrain feature layer needs to be simpified. For processing methods related to terraced terrain features, please refer to section 3.1.1.3 of this manual. For non terraced projects, this step can be skipped directly.

13.1.1.10 Step 9: Transmission lines

In this step, it is necessary to manually select the transmission line layer and tower layer. The software will automatically place the straight line elements in the transmission line into the "Candela-Center-Line" layer, place the circular or square shapes representing the towers into the "Candela-Screen-Tower" layer, and export the center point coordinates of the shapes automatically.

13.1.1.11 Step 10: Origin

In this step, the software will automatically generate a rectangular box, so that all the elements which is with the first layer name of "Candela" in the drawing are within the rectangular box, and automatically read and copy the coordinates of the bottom left corner of the rectangular box to the clipboard. This value can be entered as the "X" and "Y" values in the "Project settings" of SketchUp software.

13.1.1.12 Step 11: Final check

In this step, the software will perform a final check on all the above steps and list the steps with unprocessed items. If other layers need to be processed, users need to manually click on the previous step to return to the step that needs to be processed and manually check.

After the preprocessing guide is completed, please click the "OK" button on the interface and the software will save all processed layers to a new drawing .

13.1.2 Read origin coordinates (getzero)

Skip.

13.1.3 Convert 3D polylines to polylines (pline3trans)

If the contour lines are 3D polylines, importing them into SU may result in direct collapse. At this point, the command is required to convert the 3D polyline to the standard polyline format.

13.1.4 Convert 2D polylines to polylines (pline2trans)

When using the "Gblock" command, if the rectangle of the arrays is drawn by using 2D polylines, this command needs to be used to convert the 2D polylines to the standard polyline format.

13.1.5 Batch set the global linewidth of the polyline to 0, thickness to 0, and linetype to continuous (setplines)

This command can adjust the graphic properties to set the global line width and thickness of all graphics marked as polylines in the drawing to 0, and the line type to continuous. Generally used for preprocessing DWG topographic maps.

13.1.6 Merge available area (UnionPolyline)

This command is designed specifically for handling a large number of redline ranges exported from software such as Ovi and ArcGIS. This command is limited to merging available areas and cannot select and merge restricted areas.

Before (The middle area is an unusable hollow area)	After (Red - Available Area, Yellow - Disabled Area)

After using this command, the software will pop up the following interface:

"Area threshold": When the ratio of the intersection area of two regions to the area of a small region is lower than the set threshold, the smaller region is considered restricted, while the union of the two regions is considered available.

Before (Area threshold: 30%)	After

"Spacing threshold": For two adjacent areas without intersection, if the distance between them is less than the set value, these two areas will be merged into one available area.

Before (Spacing threshold: 2.5m)	After

After the merge operation is completed, the software will automatically classify the merged available areas into the "Candela-Region-ValidArea" layer and the merged restricted areas into the "Candela-Region-InvalidArea" layer.

13.1.7 Check polylines unclosed or Self intersecting (checkpoly)

(1) Select layer to check;

(2) Click to check, if there are any unsatisfactory areas, the list will be displayed;

(3) Click on a row in the list to locate the position that needs to be closed or modified.

Note: The closed area composed of multiple polylines needs to be merged by using the "PE"command, as detailed in section 6.6. The "Closepoly" command can also be used for processing, as detailed below.

13.1.8 Close polylines (ClosePoly)

This command can only process polyline objects. If it is a straight line, users need to use the "PE" command to convert the line into polylines (specifically: "PE", "M", convert to straight line, "J" command).

This command performs the following operations on the selected polyline object in sequence:

1) Merge polylines;

2) Close the beginning and end of polylines, and the following dialog box will pop up. When the distance between the first and last points of a polyline is less than the "Closure tolerance", it will automatically be closed.

13.1.9 Remove self intersecting, remove overlapping polylines (DeleteSelfConnect)

This function is mainly used to remove self intersecting or overlapping segments in polylines, and the following main functions are as follow.

1) Remove overlapping segments of a single polyline

Before	After

2) Remove the self intersecting section of polylines

Before	After

3) Remove completely overlapping segments between polylines (line width and thickness should be 0, the following figure is only for illustration)

Before	After

13.1.10 Close road intersections (CloseRoadCross)

This command can only process polyline objects. If it is a straight line, users need to use the "PE" command to convert the line into polylines (specifically: "PE", "M", convert to straight line, "J" command).

When dealing with road intersections, the "Deleteselfconnect" command can be used for preprocessing.

This command is mainly used to process the issue of unclosed road intersections and supports the following types:

After entering the command, select the polyline to be processed, and a dialog box will pop up:

"Max. road width": It refers the widest distance of the selected road.

"Search range": It refers greater than the maximum road width and greater than the length of the line segment that needs to be connected to a closed intersection.

In the above dialog box, fill in the appropriate values, click "OK", and the software will list the situations of unclosed intersections:

Users can click "Start", and the effect after processing is as follows:

13.1.11 Close roads end (CloseRoadEnd)

This command can only process polyline objects. If it is a straight line, users need to use the "PE" command to convert the line into polylines (specifically: "PE", "M", convert to straight line, "J" command).

When dealing with road ends, the "DeleteSelfConnect" command can be used for preprocessing.

This command is used to process the issue of unclosed road ends, with the following effects:

Before	After

After entering the command, a dialog box pops up:

"Max. road width": It refers the widest distance of the selected road.

"Search range": It refers greater than the maximum road width and greater than the length of the line segment that needs to be connected to a closed intersection.

13.1.12 Simplify polylines (SimplifyPoly)

This command aims to simplify polylines. When the points on a polyline are too dense, the drawing may become bulky and difficult to manipulate. By applying the "SimplifyPoly" command, excess points on polylines can be effectively removed, thereby reducing the size of the drawing file.

13.1.13 Convert DMTZ terraced lines to contour lines (DMTZ2DGX)

1) Applicable project: Terraced terrain, specifically referring to certain areas with only "DMTZ" layer and "GCD" layer, without contour lines.

2) In CAD, using the "DMTZ2DGX" function, in areas without contour lines but only "DMTZ" layer and "GCD" laye, contour lines are generated based on "DMTZ" layer and "GCD" laye on the DMTZ-DGX layer.

3) After generation, please check the purple lines of error lines, usually because the DMTZ adjacent to the purple lines does not have a suitable elevation point in the corresponding direction. It can be manually supplemented, and contour lines can be regenerated or directly deleted.

The "DMTZ2DGX2" command can be divided into blocks to generate "DGX" from" DMTZ" (mainly used for situations where the project is too large and the speed is slow).

13.1.14 Delete entities within and outside the range of closed polylines (DeletePolyByBound)

Users can draw a closed polyline as the boundary and then select the elements to be deleted. Next, users can decide whether to keep the elements within or outside the boundary to complete the cutting operation of the elements Compared to the original cutting commands in CAD, this command has a faster response speed and is more convenient to operate.

Before	After (deleting elements within the scope)

13.1.15 Obtain the center coordinates of circles, rectangles, and cosed polylines (getxy)

After execution, the software will automatically generate a "*.txt" document containing the coordinate information of the selected graphic elements. The "X" and "Y" coordinates in the document are separated by commas (","), while the coordinates of different elements are separated by semicolons (";").

13.1.16 Break circular road (SplitRingRoad)

After setting the road layer as a restricted area, if there is a circular road, the internal area of the circular road is also defined as a restricted area. If the internal area of the circular road needs to be used as an available area, this command can check and interrupt the circular road. If it is not a continuous polyline, the "PE" command needs to be used to merge (specifically: "PE", "M", convert to straight line, "J" command).

13.1.17 Analyze elevation (QueryElevationRange)

This function can perform elevation range statistics on the selected elements.