How to Input Surveyor’s Units and Coordinates for a Site Plan in CAD

When drafting a site plan in CAD software like AutoCAD or NanoCAD, accurately inputting surveyor’s data is absolutely necessary for creating precise boundary shapes. This guide explains how to efficiently input survey data, including distances and coordinates, while avoiding unnecessary steps like scaling from inches to feet.

Understanding Survey Data Units

Surveyors typically provide data in one of the following formats:

• Feet and Decimal Feet: For example, 150.25 feet.
• Inches or Decimal Inches: For example, 1802.5 inches.

The most common format for CAD drafting is feet and decimal feet, as it aligns with standard drafting practices and unit settings in CAD software. Knowing the unit system used in your survey data is the first step to ensuring accuracy.

Setting Up the Drawing Units

Before inputting any data, confirm that your CAD software is set to the correct unit system:

In AutoCAD:

1. Type UNITS and press Enter.
2. In the Drawing Units dialog box:
   • Set Insertion Scale to Feet.
   • Choose your desired precision for linear units (e.g., two decimal places).
3. Click OK.
4. Also in the UNITS setup you have the following. Choose the one that best suits your purposes:Systems of angle measure:

(Examples)

1. Decimal degrees 45.0000
2. Degrees/minutes/seconds 45d0’0″
3. Grads 50.0000g
4. Radians 0.7854r
5. Surveyor’s units N 45d0’0″ E

In NanoCAD:

1. Access the Units settings through the toolbar or by typing UNITS.
2. Ensure the unit type is set to Feet.
3. Adjust precision as needed.

This ensures that any coordinates or distances you input will be interpreted as feet, eliminating the need for scaling.

Inputting Survey Data

Inputting Distances in Feet and Decimal Feet

If your survey data is in feet and decimal feet, you can input it directly into the software without any conversion:

• Example: To draw a line 150.25 feet long, use the LINE command and enter the distance directly.

Inputting Coordinates

CAD software allows for various coordinate entry methods:

• Absolute Coordinates: Enter the exact point (e.g., 100,200 for X=100 and Y=200).
• Relative Coordinates: Start coordinates with the @symbol to reference the previous point (e.g., @150.25,0 moves 150.25 feet in the X direction).
• Polar Coordinates: Specify a distance and angle (e.g., @150<45 for 150 feet at a 45-degree angle).
• Surveyors Coordinates (Units): Start coordinates with the @symbol to reference the previous point (e.g., @150.25,0<n23d10m01w moves 150.25 feet in the northwest 23 degrees, 10minutes, 01 seconds direction).

Converting Data from Inches to Feet

If your survey data is in inches and it probably won’t be, convert it to feet before inputting it into the drawing. It’s better to avoid scaling by setting the units correctly and converting data beforehand.

Alternatively, if you’ve already input the data in inches, you can scale the drawing:

1. Use the SCALE command.
2. Select the objects to scale.
3. Specify a base point.
4. Enter a scale factor of 12.

Best Practices for Accurate Site Plans

1. Confirm The Units: Double-check the unit system of your survey data before starting.
2. Set The Units First: Always configure your drawing’s units to match the survey data.
3. Avoid Scaling: Input data in the correct units to eliminate the need for scaling later.
4. Use Precision: Ensure your CAD settings allow for sufficient precision to reflect survey data accurately.

If you are wanting to be, or are a drafter, math, measurements, and geometry are right in the middle of your chosen profession. By understanding your survey data’s unit system and configuring your CAD software appropriately, you can input distances and coordinates directly without unnecessary conversions. This approach saves time and ensures the accuracy of your site plan, providing a solid foundation for further drafting and design work.