dnlgalleguillos/gauge-reference

Gauge reference

"Make it look like this" is only finished when a number says so. This skill turns a reference into measurements, builds in an isolated collection, and compares every render against the target.

Authority order

1. What the user wrote (explicit values and rules).
2. Node screenshots: they decide connections and settings.
3. The reference render: it decides appearance. Anything you infer rather than read is an assumption: list it in your reply and let the user confirm.

Workflow

1. Begin an isolated workspace: scripts/workspace.py action=begin name=match1 (saves camera, world, engine, view settings; creates the collection).
2. Read the screenshots with references/reading-node-screenshots.md: write the graph as text (node, key values, links) before building. Small numbers in a screenshot are easy to misread; flag the uncertain ones.
3. Measure the reference: scripts/ref_report.py image=ref.png gives mean luma, contrast, clipping, saturation, a palette of sRGB hex with shares and a 4x4 sharpness map (where the focus is). scripts/ref_colors.py reads exact colours at points; the hex is what you see, linear is what goes into a shader.
4. Build the nodes with gauge.node_build / gauge.gn_make (see gauge-materials, gauge-geonodes), then re-read what you built with scripts/node_text.py and compare it with your transcription.
5. Render small, then scripts/ref_match.py image=mine.png reference=ref.png. Each failed check carries one correction with a number: exposure in stops (multiply light by 2^-stops), contrast ratio, tint per channel, structural error.
6. Change one thing, render, measure again. Stop when the gate passes (defaults: exposure within 0.35 stops, contrast ratio 0.85-1.15, tint within 0.04, error <= 0.08).
7. End: workspace.py action=end restores the scene and lists what it would delete; pass confirm=true only when the user agrees.

Tools

Script	Answers
ref_report.py	what is in this image (and how far is it from another)
ref_colors.py	exact colour at a point
ref_match.py	is my render close enough, and what to change
node_text.py	what does this material / group / world / compositor tree contain
workspace.py	begin / end without leaving a mess

Rules

• Match structure first (framing, shapes, light direction), colour second, detail last.
• Fix exposure before colour: a 1-stop error shifts every colour measurement.
• A render at 50 % size and 24 samples is enough to judge all of the above.
• Reference images with compression or a different gamma are not exact: trust the palette and ratios, not single pixels.