Vegetation cover is critical in supporting our lives by maintaining many ecological and environmental services. As part of the vegetation cover, forests are the most essential components of the carbon cycle on the Earth. Canopy height is a critical piece of data needed for calculating the ecological and silvicultural variables of the forest. Since the forest canopy is the first/last frontier interacting with the atmosphere and incoming from space electromagnetic radiation, this study investigates using Digital Elevation Models (DEMs) to map canopy heights. A comparison of the Canopy Height Models (CHMs) with a reference CHM and Digital Terrain Model (DTM) was performed in this study. The investigated DEMs include SRTM, ALOS World3D30 (AW3D30) and WorldDEM (TM). Results show an underestimation of CHMs and significant variations between the DEMs used. Consistent for all DEMs, the spatial resolution of 30 m produced the CHMs' RMSE of 15.35 m, 16.95 m, and 16.49 m for AW3D30, SRTM and WorldDEM (TM), respectively. In addition, the largest CHM bias was for the SRTM. The ratio between the obtained CHMs and the reference CHM can provide a first-hand method to estimate a suitable correction to the actual forest height. The study was conducted on a flat terrain covered by pristine rainforest in Brunei Darussalam, Borneo. The forest is evergreen, and the phenological cycle is barely recognizable throughout the year. These facts are essential for the research since the DEMs were collected at different months/years.