You can create a control point in the Dusty app from any two lines that are not parallel, even if they don't touch each other. Select the two lines and choose Create Control at Intersection. The app places the control point where the two lines meet, or would meet if extended.
The lines don't need to be printed. This is how operators rebuild control points when, for example, a surveyor marks them at a set distance from grid lines and sends only the offset distances, with no CSV file.
What you need before you start
- The surveyor's marks on the floor with the offset distances for each control point: the two grid lines it's measured from, the distance from each, and which side of each grid line it's on (for example, 16'-6" south of grid E and 5'-0" west of grid 5). This usually comes as a marked-up drawing from the surveyor.
- Grid lines in the layout file. Open the Layers panel and make sure the grid layer is visible.
Example: Create the offset lines from grid lines
Repeat these steps for both grid lines that define the control point.
- Select the grid line. Only one line can be selected. If lines are stacked, deselect all and reselect just the grid line.
- Hold your finger on the side of the line where the control point is and select Create Offset Line from the menu. The side you picked sets the direction.
- Enter the offset distance. Use a number greater than 0.
- The new line should be parallel to the grid line, on the correct side, at the distance you entered.
Create the control point
- Select the two lines that define the control point.
- Go to the Station menu, select Control Points, and open the Control Points menu; or press and hold on the layout canvas.
- Select Create Control at Intersection.
- Name the control point. The app suggests CP01 and counts up from the last name used. Change it to the name on the surveyor's drawing so the app matches the mark on the floor.
Repeat for each control point.
Check each control point before you station
- Zoom in and confirm the control point sits where the two lines meet, or where they would meet if extended.
- Compare each point with the surveyor's drawing: the right two grid lines, the right distances, and the right side of each line.
- After you station, look at the distance error for each control point. One point with a much larger error than the others usually means it was built from the wrong grid line, the wrong side, or the wrong distance. See Understanding Station Information: Reading Distance Errors and Station Errors to Remove Bad Control Points.
Common issues
| What you see | Likely cause | What to do |
|---|---|---|
| Create Control at Intersection isn't available | The two selected lines are parallel, or you don't have exactly two lines selected | Select two lines that run in different directions. |
| One control point has a high distance error after stationing | The offset was taken from the wrong grid line, on the wrong side, or at the wrong distance | Recheck that point against the surveyor's drawing, delete it, and create it again. |
| Every control point has high errors | The grid lines in the file may not match the grid lines on site, or the file isn't aligned with the surveyor's drawing | Confirm with your VDC team that the file's grid lines match the drawings the surveyor used before you print. |
Related articles
- How to Create Manual Control Points from Printed Intersecting Lines
- How to Create an Offset From a Layout Line on the Tablet
- Control Point Creation Requirements for Surveyors (Placement, Count, and CSV Format)
- What Are Control Points and Why Dusty Needs Them
- What Are Grid Lines and What Are They For?