A contour survey is a way to easily visually understand the vertical and horizontal shape (the “topography”) of your land. By understanding the land contours, you can easily visualise or map how water will flow across and through the property when it rains, where it will collect, where it might erode the soil and many other important water flow characteristics. From this simple base, you can even develop water flow models, stream maps and determine the best places to create dams and silt traps.
Contour surveys need to be conducted by a registered surveyor, right? Well, not all the time. A registered surveyor is required if the contour survey data is being used for construction or engineering purposes, or if the boundary data is being registered on a government cadastral (land title) system. Otherwise, surveyor certification is generally not required. We partner with a registered surveyor (yours or ours) where certification is required.
Contour surveys by a registered surveyor are more accurate than drone surveys, right? Well, not really. In theory, a surveyor’s PPK measurement system can achieve accuracy 5mm, but in reality the average accuracy used by surveyors on ground surveys is around 10-15mm, which is very similar to the accuracy achieved by a well-designed drone survey (15-25mm). Ground surveys typically measure around 5-6 points per square metre or less. Aerial surveys can measure 100s of points per square metre. You do the math!
A registered surveyor is faster and cheaper than a drone survey, right? Not at all! The area that a ground survey team can cover in a day can be covered by an aerial survey in 1-2 hours. The area a ground surveyor would take a week to complete can be done with a drone survey in a day or two. Both methods have similar processing times, although drone survey results are usually ready in a few days, while ground survey data can take weeks to process and deliver.
Precise aerial land mapping can only be achieved using LIDAR, right? Well, not really. We have used both and generally speaking any terrain with less than 50% tree cover can be mapped using a standard drone mapping camera with a reasonable degree of accuracy. Standard drone mapping relies on making connections (extrapolation) between visible ground points, just as a traditional ground survey does. Where there are doubts about accuracy due to long grass or thick vegetation, we can often underpin a drone mapping survey with government LIDAR data to confirm results (takes longer, but can be done). In reality, LIDAR mapping is generally more expensive, more time-consuming and can be less accurate than professional orthometric drone mapping. Please feel free to chat with us about this if you have concerns.