Modeling Surface Topography: A Comparative Analysis of GPS, LiDAR and USGS Digital Elevation Models

Wagaman, Mark¹ (1) Veritas DGC, Denver, CO

Surface topography models are beneficial for various phases of oil and gas exploration which include planning 3D seismic surveys, fulfilling regulatory requirements, determination of drilling rig locations, pipeline routes and production facilities. These surface models, called DTM’s (digital terrain models) can be constructed from the publicly available USGS DEM (digital elevation model) dataset or from remote sensing techniques such as LiDAR (Light Detection and Ranging) and aerial photography. The decision as to which type of product to use includes considerations of cost, availability, intended purpose and vertical accuracy of each product.

LiDAR provides a high resolution, extremely accurate digital elevation model that includes a first return layer depicting tree canopy or culture. It needs to be contracted, scheduled, acquired usually only in favorable conditions and then processed into a final product. USGS DEM products are readily available and can be obtained from the internet. While published specifications exist for the vertical accuracy of USGS DEM products, they are based on limited ground control and subject to some degree of uncertainty.

Completed seismic surveys provide an ideal environment to investigate and contrast the vertical accuracy of DTM models, especially when a LiDAR survey has been acquired over the location. Dense ground control in the form of surveyed source, receiver and control base stations provide the basis to conduct a comparative analysis of elevation values. An analysis of elevations, along with an examination of various derived products such as slope conditions and illumination models illustrate the type of vertical accuracy to be expected from the various DTM products.

AAPG Search and Discovery Article #90055©2006 AAPG Rocky Mountain Section Meeting, Billings, Montana