The Digital Camera Opacity Technique
WHAT IS DCOT?
DCOT, the Digital Camera Opacity Technique, is the digital-camera method used to determine plume opacity from images rather than by estimating opacity solely by eye. DCOT provides a standardized way to capture, analyze, and document visible emissions observations using digital imagery. It is defined by ASTM D7523 and approved by EPA to be used in lieu of Method 9 for all opacity monitoring needs.
If you see DCOT referenced in a permit, inspection report, regulatory correspondence, or visible emissions procedure, it refers to the Digital Camera Opacity Technique.
DOCS II is a DCOT system.
Every DOCS II observation is built from the same four parts.
1. Certified image capture
The camera system is configured and operated according to the applicable certification requirements, including the camera settings, viewing conditions, and positioning needed to produce a valid Method 9 observation.
2. Digital opacity analysis
The captured image is analyzed to determine plume opacity using the procedures and analysis requirements established for the technique.
3. Field data
The observation includes the information needed to understand the conditions under which it was collected — including the observer's position, viewing direction, distance from the source, weather, and solar conditions.
4. Certified Operator
One 4-hour DOCS II training course, delivered virtually. Trained in the principles of visible emissions and in DCOT-specific procedure.
Who can take a DCOT observation?
A DCOT operator completes one 4-hour DOCS II training course and stays certified for as long as they use the DOCS II camera. Certification is on the configuration and the operator both — neither alone is sufficient.
ANATOMY
Anatomy of an observation
Certified capture
A camera configuration certified under ASTM D7523, recertified every 3.5 years
Calibrated analysis
Per-region contrast and luminance scoring, checked against known opacity values from smoke school
Field metadata
Position, bearing, distance, weather and solar angle, logged at the moment of observation
A permanent record
A record that can be reviewed after the field observation is complete.
WHAT WE PROVIDE - VIRTUAL TECHNOLOGY LLC
The leaders in DCOT compliant Digital Opacity Camera System
For stationary and fugitive sources.
DOCS II app for smartphone, with map-based, sun position, and weather setup
Certified camera configuration, supplied and maintained by us, recertified every 3.5 years through the national smoke school network
Analysis and analyst verification on every observation
The 4-hour DCOT training course ALT-082 requires, delivered virtually
Records export for permit reporting and agency submittal
Certification records and technical support through a proceeding, if a Method 9 observation is challenged
Bring us an emissions source and we'll show you how to capture it.
Tell us what you operate or regulate, and we'll walk through a real observation end to end — capture, analysis, confirmation, and what you're left holding.