SIM GEOMETRY measurements · compatibility · cost

Guide 02 / field geometry

iRacing FOV calculator and triple settings

For a single display, map the physical horizontal span. For native triples, map the full visible envelope across all three projections—not the center panel alone.

iRacing is one of the cases where the number in the field and the physical layout can be connected directly, but the connection changes with screen mode. The published conventions record identifies its FOV axis as horizontal and its basis as the full rendered span. On a single display, that maps to the calculator’s horizontalSpan. With native three-projection rendering, it maps to visibleEnvelope: the angle from the leftmost visible image edge to the rightmost visible image edge across the complete rig. The evidence grade remains medium because the official material establishes the geometry workflow and multi-projection behavior (official iRacing setup evidence), while the explicit horizontal-axis naming rests on converging secondary evidence rather than a first-party sentence.

What the iRacing calculator field represents

The official triple-monitor instructions direct the driver to select a three-screen display mode, enter screen type and physical measurements, and use the Field of View Calculator under the Monitor section (official iRacing triple-monitor instructions). That makes the control geometry-driven: monitor width, bezel width, viewing distance, and side-screen angle describe the physical arrangement from which the rendered view is derived (official setup field list). The resulting driving FOV is expressed in degrees; the conventions record maps it to horizontal full span, with the evidence qualification above.

This is not the same operation as choosing a camera position. iRacing’s Camera Tool documentation describes the in-sim bracket controls for driving-camera FOV and separate camera-editing controls (official Camera Tool documentation). Changing projection angle and moving the virtual camera can both alter what appears in the frame, but they do not preserve the same perspective. Establish the physical FOV first. Use camera position for the remaining seating or framing task without treating it as a replacement distance.

Why “Render scene using 3 projections” matters

The official setup distinguishes ordinary spanning from rendering the scene with three projections and instructs triple users to enable that mode (official three-projection setup). In geometric terms, each monitor receives its own camera frustum aligned to that panel. A straight object crossing a seam can then continue through the change in monitor angle without asking one flat projection to pretend all three panels share a plane.

iRacing’s release notes document a 270-degree maximum for three-monitor driving-camera FOV, alongside changes associated with triple-screen rendering (official 2020 Season 4 release notes). That is a software limit, not a target and not evidence that a physical rig should wrap 270 degrees. Enter measured geometry; let the layout determine the required envelope. No verified step size or single-screen maximum is available, so do not infer either one.

Match the result to iRacing

For one flat display, the calculator draws rays from the eye point to the two visible horizontal edges and reports the included angle. That is horizontalSpan, and it is the relevant single-screen output for the iRacing record. A curved single display uses the visible chord, radius, and center distance to locate its nearer edges, then reports the physical horizontal span. It remains a physical baseline: one rectilinear projection cannot align with every point of a curved surface simultaneously.

For identical triples, the calculator constructs the center panel and both yawed side panels in a top-down ray model. centerSpan is only the middle active image. visibleEnvelope reaches the outer active edge on each side and therefore describes what all three projections collectively cover. The iRacing dataset mapping explicitly chooses that full envelope for triples. Copying the center span into the driving field would discard both side projections and understate the intended view.

Bezels do not add visible scenery. They create two physical gaps between active images. The calculator reports the angular seam occlusion separately and can estimate hidden pixels when resolution is present. This matches the purpose of iRacing’s documented bezel-width input: geometry has to account for the cabinet interruption while preserving the world behind it (official bezel-width guidance). Measure from the visible image edge to the cabinet edge on one side of one monitor; the seam between two identical cabinets contains two such sides.

A measured workflow

  1. Set the seat and screen positions, then measure from the midpoint between the eyes to the center of the center panel’s visible surface.
  2. Measure active image width rather than accepting the marketed diagonal as exact. For triples, measure bezel per side and the side angle from straight.
  3. Open the prefilled state below and replace its dimensions. Select recommended yaw only if you want to compare against the published chord-tangent convention; otherwise enter the measured angle.
  4. Read horizontal span for a single display or visible envelope for triples. Keep the ±10 mm sensitivity endpoints with the number.
  5. In iRacing, use the official monitor setup and geometry calculator, and enable three projections for the native triple workflow (official configuration procedure). Compare the game result with the same physical inputs instead of forcing a value copied from a different rig.

Open the prefilled iRacing triple-screen example

Avoid unverified configuration-file claims

The evidence record names Documents\iRacing\app.ini for view-related configuration and rendererDX11Monitor.ini for monitor geometry, but it leaves the executable FOV key null. The sampled monitor file exposes screen dimensions, angle, bezel, and per-monitor rendering state (dataset-linked rendererDX11Monitor.ini example); it is not evidence for a degrees key. Because community references to another key lack direct support, use the documented UI path and calculator.

Reading disagreements responsibly

If iRacing and this tool differ, first confirm that both received the same visible width, center distance, bezel definition, and side angle. Then confirm the render mode. A center-panel angle, a full visible envelope, and a bezel-corrected rendered span are different quantities even when each is internally calculated correctly. Round only at the input boundary the game provides, and retain the higher-precision physical record outside the game.

The practical rule is compact: one screen uses the horizontal physical span; native three-projection triples use the full visible envelope. Everything else—seat framing, horizon, mirrors, and camera translation—is a separate adjustment and should not be used to conceal a geometry mismatch.

External sources