Calculators

Calculators sits in the Field section of the sidebar, and the command palette finds it if you type "fov", "storage", "lens" or "terabytes". Two tabs: Field of view and Video storage.

Both also exist publicly at fieldmarkup.com/tools with no login, so you can send a customer or a subcontractor a link without giving them an account.

Pick the resolution, the sensor format and the lens, and it gives you the horizontal and vertical angle, how wide the scene is at your chosen distance, the pixel density in pixels per foot or metre, and which DORI band that lands in — detect, observe, recognise or identify.

Two things it does that a spec sheet will not:

• It checks the angle you type in. If you tick "I have the angle from the spec sheet" and enter a figure that looks like a diagonal, it says so. Spec sheets usually headline the diagonal because it is the bigger number, and using it as a horizontal makes every cone too wide.
• It shows the blind spot. Set the mounting height and the downward tilt and the side view draws the ground the camera cannot see beneath itself — the thing a plan view is silent about.

Add a group of cameras for each different spec on the job — eight 4MP domes here, four 4K bullets there — then set the codec, the retention period and how busy the scenes are. It gives you the total terabytes, how many drives of a given size that takes, and the stream bandwidth in Mbps.

The bandwidth figure is worth reading separately from the storage one. It sizes your switch and uplink, and recording on motion does not reduce it: the cameras stream continuously whether the recorder is writing or not.

Drive counts are worked out against what the recorder will report, not what the box says. A "4 TB" drive shows up as 3.64 TiB, and sizing off the larger number leaves a 30-day retention spec running about 27 days.

The field-of-view calculator uses the same maths the editor uses to draw cones on a plan, so a figure you get here and a cone on a drawing cannot disagree. Once cameras are placed in a project, the coverage is drawn to scale with overlap shaded — see camera FOV cones.

Treat every number as geometry rather than a promise about picture quality. Low light, compression, a dirty dome and a moving subject all cost detail the arithmetic does not know about, so design with margin.