# Tracing photos and drawings

Place ports by clicking on a straight-on photo or a datasheet drawing of a face. Photos are processed on your devices and never stored by Rack Maker.

Source: https://rack-maker.cbnsndwch.dev/docs/modeler/tracing

## How tracing works

In **Faces and ports**, each face can have one image under it: a photo of that face, or a page of a datasheet with a drawing of it. Once the image is lined up with the face, you place ports, zones, LEDs and buttons by clicking on it, and their positions come out in millimetres.

A device can keep several photos, and the modeler can find the ports on a traced one for you: see [Photos and port detection](https://rack-maker.cbnsndwch.dev/docs/modeler/detection).

> **Your photos stay on your devices:**
>
> Photos are processed in your browser and kept in this browser. Rack Maker never stores them, and they are never part
> of a draft, a published entry or its model file. What is kept with the device is numbers only: sizes and positions
> in millimetres.

## Tracing a photo

### Take the photo

Photograph the face as straight on as you can, the whole face in view. A ruler or calipers in the picture helps you check your numbers.

### Add it to the face

Open the face's tab, then **Photo…** and pick the file.

### Click the four corners

The modeler asks for each corner in turn: bottom-left, bottom-right, top-right, then top-left, as seen from outside. The photo is then straightened and scaled to the face's size, which corrects for a photo taken at a slight angle.

![A photo of the left side added to the face, with two of its four corners clicked and the modeler asking for the next one](https://rack-maker.cbnsndwch.dev/docs/shots/modeler/trace-corners-light.webp)

*Click the face's four corners on the photo, in the order it asks.*

### Place ports on it

The straightened photo now shows under the face. Pick a tool and click on each opening. Drag a corner on the photo to adjust it, or use **Click the corners again** to start over.

![The front face of the Edge Router with its photo straightened under it: ports, a LED and a vent line up with the photo, and the photo controls above](https://rack-maker.cbnsndwch.dev/docs/shots/modeler/trace-photo-light.webp)

*The photo, straightened and scaled to the face.*

Set the body's size in **Shape and size** first: the photo is scaled to the face you measured, so the face's width and height must be right.

## Tracing a datasheet drawing

A technical drawing in a datasheet is already straight on, so instead of corners it needs a scale and a position.

1. Open the datasheet in **Name** with **Read a PDF…** (see [Datasheets](https://rack-maker.cbnsndwch.dev/docs/modeler/datasheets)).
2. In **Faces and ports**, pick the page with the drawing and choose **Use the page**.
3. **Scale**: click both ends of a labelled dimension, type its length in mm, and choose **Set scale**.
4. **Place the face**: click the bottom-left corner of the face on the drawing.

Drag the outline to move the face on the drawing if it needs a nudge.

![The rear face traced on a datasheet drawing: page 2 of the datasheet under the face, scaled by its dimension and placed by its corner](https://rack-maker.cbnsndwch.dev/docs/shots/modeler/trace-drawing-light.webp)

*A datasheet drawing under the rear face.*

## Showing and removing the image

- **show**: a slider for how strongly the image shows under the face.
- **Hide the image** and **Adjust**: tuck the image away once it is lined up, and bring it back.
- The bin button removes the face's image.

## Faces you can't trace

A photo can't be traced on the round side of a cylinder: measure positions along the surface instead. A face that carries nothing on its shape, such as the walls of an extruded bracket, says so. See [Shapes and parts](https://rack-maker.cbnsndwch.dev/docs/modeler/shapes-and-parts).

## What is sent, and what isn't

| What                                                  | Where it goes                                                                                                                               |
| ----------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------- |
| The photo                                             | Processed in your browser, downscaled to at most 2,000 px on its long side, and kept in this browser's storage. Never stored by Rack Maker. |
| A datasheet page used as a drawing                    | Rendered in your browser, kept like a photo.                                                                                                |
| The corners, the scale and the image's size in pixels | Kept in this browser with the photo.                                                                                                        |
| Your measurements (sizes, port positions, finishes)   | Saved to your account as your draft, and published with the entry.                                                                          |
| The model file                                        | Built from your measurements only. No photo textures.                                                                                       |

### Between your own browsers

With live sync, a traced face can follow you to your other signed-in browsers:

- The corners and the image's size go to your other browsers that have the draft open, so they line up the same way.
- A browser that doesn't have the photo asks your others for it. The photo then passes through Rack Maker's server **in transit only**, while both browsers are open, and is never stored on the way. The receiving browser keeps its own copy.
- If no other browser with the photo is open, it doesn't arrive: open the draft on the device that has it, add it again, or remove it.

Under a traced face the modeler shows **Waiting for your other device**, **Receiving the photo from your other device…** or **Received from your other device**. See [Live sync](https://rack-maker.cbnsndwch.dev/docs/modeler/live-sync).

### With your AI agent

An agent reads your photos on your computer and sends only numbers: the photo's size in pixels and the face's four corners on it, or a drawing's scale and origin. The server keeps those numbers with the agent's working copy, to turn points on the photo into millimetres. It has no way to receive a photo. See [How an agent measures](https://rack-maker.cbnsndwch.dev/docs/agents/measuring).

## Taking colours from a photo

In **Finishes**, a traced photo can be clicked to take the colour under the pointer for the body, a zone or the feet. The colour is read in your browser; the photo goes nowhere.