Aerial LIDAR Surveying

“Serving the entire Southeast”

Fast Mapping for Large Properties

Walk a 500-acre tract with survey equipment and you’ll spend weeks collecting elevation data.

Fly that same property with LIDAR and you’ll capture millions of precise elevation points in a few hours. 

For large properties, difficult terrain, or projects needing dense data fast, aerial LIDAR changes the economics and timeline of surveying.

LIDAR stands for Light Detection and Ranging. It’s essentially radar using laser light instead of radio waves. 

An aircraft-mounted LIDAR system fires hundreds of thousands of laser pulses per second at the ground. Sensors measure how long each pulse takes to bounce back. Distance calculations become elevation measurements.

 Position data from GPS turns those measurements into precise x, y, z coordinates for every point.

How LIDAR Actually Works

The LIDAR sensor sits in an aircraft flying predetermined paths over the survey area. The system fires laser pulses at the ground in a sweeping pattern perpendicular to the flight path. 

Some pulses hit the ground. Some hit tree canopy, buildings, or other objects above ground.

The clever part: LIDAR sensors record multiple returns from each pulse. The first return might be a tree canopy.

 Later returns might be branches, undergrowth, and finally bare ground. Software processing filters return to identify ground points versus vegetation and structures.

This lets LIDAR “see through” tree canopy to measure ground surface – critical for surveying forested properties. 

Traditional aerial photography can’t do this. Satellite imagery can’t do this. Only LIDAR penetrates canopy to map terrain beneath vegetation.

Position and orientation systems in the aircraft record its exact location and attitude for every laser pulse.

This ties all measurements to real-world coordinates. When processing is complete, you have millions of points with known x, y, z positions accurate to a few inches.

When LIDAR Makes Sense

Large properties benefit most from LIDAR efficiency. Traditional ground surveys bill by time and complexity.

Surveying 500 acres with conventional methods might take a crew three weeks and cost $75,000-$100,000. 

LIDAR might survey the same property in half a day for $35,000-$50,000 while capturing vastly more data.

Difficult terrain drives LIDAR advantages. Steep mountainsides, dense forests, and properties with limited access are slow and expensive to survey conventionally. 

Surveyors fight terrain and vegetation. Equipment has to be carried to remote areas. Progress is slow.

LIDAR doesn’t care about terrain difficulty. Steep slopes, dense vegetation, remote areas – the aircraft flies over all of it at the same speed and cost. 

Properties that would take weeks to survey on foot get surveyed in hours from the air.

Linear projects favor LIDAR economics – roads, rail lines, power lines, pipelines, rivers. These projects need topographic data along narrow corridors that might stretch for miles. 

Ground surveying crews would spend weeks moving along the corridor. LIDAR flies the entire length in a few hours.

Rapid response situations use LIDAR when time matters more than cost. Flood mapping after disasters. Landslide assessment. Emergency planning. 

Projects where waiting two weeks for ground surveys isn’t acceptable but answers need to be accurate.

What LIDAR Delivers

The primary deliverable is a point cloud – millions or billions of individual points with precise x, y, z coordinates. 

Point density varies with project specifications. Standard LIDAR might collect 2-8 points per square meter. High-density LIDAR can deliver 20+ points per square meter.

From point clouds, we generate traditional survey products. Contour maps showing terrain shape. Digital elevation models for engineering design. 

Three-dimensional surface models. Cross-sections along any line you specify. Volumetric calculations.

We can separate above-ground features from bare earth. One dataset shows ground surface for engineering design. 

Another shows vegetation height and structure for forestry or habitat analysis. Another shows buildings and structures for asset inventory.

Deliverables come in formats engineering teams use – LAS point cloud files, CAD-compatible surface models, GeoTIFF rasters, shapefiles.

Data integrates directly with design software and GIS platforms.

Accuracy and Limitations

LIDAR accuracy depends on multiple factors – aircraft altitude and speed, LIDAR sensor quality, GPS positioning accuracy, scan density, ground surface characteristics, and processing methods.

Typical vertical accuracy runs 4-6 inches under good conditions – open terrain with firm ground surface and good GPS satellite geometry. 

Horizontal accuracy is similar but slightly less stringent. This meets requirements for most civil engineering, planning, and environmental work.

Accuracy decreases in certain conditions. Dense vegetation reduces the number of laser pulses reaching bare ground, making ground surface determination less precise. 

Soft surfaces like loose soil or sand produce less distinct laser returns. Water absorbs laser light, so LIDAR doesn’t penetrate water surfaces to measure underwater topography.

Ground control improves accuracy. We establish survey monuments with precise coordinates and elevations, then verify LIDAR data matches those control points. 

Adjustments compensate for systematic errors in aircraft positioning or sensor calibration.

LIDAR Versus Traditional Ground Surveys

Ground surveys provide higher accuracy at specific points. When you need sub-inch accuracy for structure foundations or precise utility locations, ground surveys deliver better results. 

LIDAR’s 4-6 inch accuracy is excellent for terrain mapping but not precise enough for some applications.

Ground surveys capture information LIDAR misses. Property boundaries require finding monuments and markers that LIDAR can’t identify. 

Buried utilities don’t show in LIDAR data. Cultural features like fences, signs, or small structures might not show distinctly in point clouds.

LIDAR captures information ground surveys can’t economically provide. The sheer density of data – millions of points – reveals terrain details ground surveys would take forever to map. 

Subtle drainage patterns, minor topographic variations, and complex terrain shapes show clearly in LIDAR data.

The best approach often combines methods. LIDAR provides comprehensive terrain data economically. 

Ground surveys establish control, define boundaries, and locate critical features needing high precision. Used together, they deliver complete site information efficiently.

North Georgia Applications

Mountain terrain makes LIDAR particularly valuable here. Steep forested slopes that are slow and dangerous to survey on foot get mapped efficiently from the air. 

Ridge lines, valleys, and complex mountainous topography show clearly in LIDAR data.

Forestry operations use LIDAR to assess timber stands. Point cloud data shows not just ground elevation but canopy height and structure. 

This helps estimate timber volumes, identify harvest areas, and plan logging roads.

Flood mapping needs accurate terrain data across large watersheds. LIDAR surveys entire creek valleys efficiently, capturing terrain detail needed for hydraulic modeling and floodplain delineation.

Transportation projects – new roads, road improvements, bridge replacements – benefit from LIDAR corridor mapping. 

The entire project area gets mapped at once, providing comprehensive data for design and environmental analysis.

Project Planning and Specifications

LIDAR project planning starts with defining required accuracy and point density. Rough terrain reconnaissance might need only 2-4 points per square meter. 

Detailed engineering design might require 8-12 points per square meter. High-resolution mapping for special applications might specify 20+ points per square meter.

Higher point density costs more because it requires slower flight speeds or more flight passes. Specifications should match actual project needs. 

Over-specifying wastes money. Under-specifying delivers inadequate data.

Weather and timing matter. LIDAR flights require clear conditions with good visibility.

Leaf-off conditions (late fall through early spring) work better for forested areas because more laser pulses reach the ground through bare branches. 

Projects needing leaf-off data must wait for the right season.

Processing and Deliverables Timeline

LIDAR data collection happens quickly – hours or days for most projects. Processing takes longer – typically 2-4 weeks for standard projects, longer for complex projects requiring extensive editing or specialized analysis.

Processing involves cleaning point clouds to remove noise and artifacts, classifying points as ground versus non-ground, generating surface models and contours, and creating specified deliverables. 

Quality control checks verify accuracy meets specifications.

Rush processing is possible but costs more. Standard processing uses automated workflows with spot checking. Rush processing requires more manual review and dedicated resources.

Cost Factors

LIDAR costs vary with project size, required point density, accuracy specifications, urgency, and mobilization distance. Larger projects cost less per acre because fixed mobilization costs spread across more area. Mobilizing LIDAR equipment from distant bases adds costs.

Typical costs run $100-$300 per acre for standard projects. Small projects (under 100 acres) might cost more per acre due to minimum mobilization charges. 

Very large projects (thousands of acres) might cost less than $100 per acre.

Ground control surveys add costs – typically $2,500-$5,000 depending on site size and accessibility. 

Projects requiring high accuracy need more ground control points. Easily accessible sites cost less for ground control than remote mountain sites.

Integration with Other Surveys

LIDAR supplements rather than replaces other surveys. Boundary surveys establish property lines – LIDAR doesn’t do that.

Utility locating identifies underground infrastructure – LIDAR only shows surface features.

Combined survey packages use LIDAR for terrain data and ground surveys for boundaries, utilities, and precision measurements. 

This delivers complete site information more efficiently than ground surveys alone.

For large development projects, combining LIDAR with ground surveys early provides comprehensive baseline data.

 Engineering design builds on LIDAR terrain models. Construction surveys reference boundaries and control established by ground surveys.

Quality Control

We verify LIDAR accuracy through multiple methods. Ground control points with known coordinates get compared to LIDAR elevations. Differences show actual accuracy achieved.

Visual inspection checks point cloud quality. Artifacts, noise, data gaps, and classification errors get identified and corrected.

Surface models get compared to point clouds to ensure generated surfaces accurately represent measured points.

Overlap between flight lines gets checked. Adjacent passes should agree within accuracy specifications. Discrepancies indicate positioning errors or processing problems that need correction.

Long-Term Data Value

LIDAR data captured for one project often serves future needs. The point cloud remains available for generating new products – different contour intervals, cross-sections along new alignments, surface models for expanded areas.

Repeat LIDAR surveys show change over time. Compare surveys from different years to measure erosion, track vegetation growth, monitor landslide movement, or document construction progress.

Point cloud data archives well. As software capabilities improve, you can reprocess old LIDAR data using new techniques to extract information that wasn’t feasible when data was collected.

Why LIDAR Matters

Aerial LIDAR makes comprehensive topographic surveying feasible for large properties and difficult terrain. 

Projects that would be economically prohibitive with ground surveys become affordable. Projects that would take months get completed in weeks.

The trade-off is slightly lower accuracy than ground surveys and inability to capture certain features. 

For most civil engineering, planning, and environmental applications, LIDAR accuracy is more than adequate and the speed and data density advantages outweigh limitations.

The Land Surveying Company provides aerial LIDAR surveying services throughout Georgia, Tennessee, Alabama, and Kentucky. We coordinate LIDAR data collection, process point clouds, and deliver terrain data in formats engineering teams can use immediately.

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We are a land surveying firm in Georgia dedicated to fast and friendly service in Georgia, Alabama, Kentucky and Tennessee. We service residential, commercial and industrial surveys.