Edit

Edit changes named parts of one existing image. It requires a source, at least one marked region, and one prompt that references every unique region name.

Choose a source image

Select Edit, then choose the image under Image to edit.

You can:

• drop or select an image from your device;
• choose a render or upload already in CAD Scene;
• use the latest successful render.

The selected image is the source that Edit modifies. A composer reference image is only extra visual guidance. Read Image roles and source-image preparation before choosing a difficult source.

Changing the source clears the current canvas and marked regions. Choose the source before painting.

Mark a region

Use the image tools to identify every area that may change.

1. Choose the source before drawing. A source change clears the canvas.
2. Mark each change with Rectangle or Brush. Keep every area tight.
3. Review the automatic names. Edit any name that needs more context.
4. Write one prompt that mentions every unique name as a distinct reference.
5. Review the source, regions, model settings, and output count. Then select Send.

• Rectangle marks a rectangular area and is selected by default.
• Brush paints a freeform area.
• Eraser removes painted mask pixels.
• Undo and Redo step through mask changes.
• Clear all removes every marked region after confirmation.

The brush-size control changes the Brush and Eraser width. Nearby strokes can meet one or several existing regions. CAD Scene pauses the completed mark and asks how to resolve it:

• Extend Region A adds the mark to the one region it meets.
• Merge 2 regions combines every region the mark meets. The oldest region keeps its name.
• Create new region keeps the mark as a separate named region, even when its bounds overlap another region.
• Discard stroke removes the pending mark.

The pending mark is only a preview. It is not part of the saved canvas, region count, mask export, or Send input until you choose Extend, Merge, or Create new. The canvas and its controls stay locked while the choice is open.

Select Group nearby strokes automatically with Extend or Merge to remember that grouping choice for the current source image. Later nearby marks extend one region or merge several without asking. A checked footer control shows when automatic grouping is active. Clear it to restore the choice.

The region cap follows the selected model's Edit capability. Every current model supports up to eight regions. At the cap, Rectangle and Brush stop adding regions. Eraser, Undo, Redo, Clear all, and region deletion remain available. If a model switch leaves too many regions, remove the stated number or choose a compatible model. CAD Scene preserves the existing work instead of deleting or merging it.

Overlapping regions keep separate names and bounds, but they share editable pixels. Write compatible, concrete instructions for the shared area. Tighten the marks when two requested changes cannot coexist.

Static example: Mark a tight rectangle around each intended change. CAD Scene assigns Region A and Region B. One prompt references both names.

On larger screens, keep the Edit panel open when sending. Closing it removes the active canvas from the page, so CAD Scene asks you to reopen and review the regions.

Name each region

CAD Scene names new regions Region A, Region B, and onward. After Region Z, the sequence continues as Region AA, Region AB, and so on.

Names are editable control references. They are never intended as readable text inside the image. Keep every name non-empty and unique.

Names remain attached to the marked area during normal delete, Undo, Redo, and canvas remounts. Deleting a region does not rename the survivors. A later region continues the sequence instead of reusing a deleted name.

You can keep the automatic names. Use a more descriptive name only when it makes the prompt easier to read, such as North wall or Lobby doors.

Write the Edit prompt

The Edit prompt is required. Mention every unique region name as a distinct, unquoted reference. Then state the change for that area.

In Region A, replace the ceiling with oak boards. In Region B, replace the people with dogs.

The names tell CAD Scene which marked areas the sentences address. They do not ask for the words Region A or Region B to appear in the result.

Put exact new readable scene text inside straight double quotes:

In Region A, change the sign to "Library". In Region B, keep the existing lettering.

Only the quoted word Library is requested as new readable text. Existing scene text stays unless the prompt asks to change or remove it. A name mentioned only inside quotes does not count as a region reference.

After an invalid Send, CAD Scene keeps the draft and opens Before you send with every fix. Select Review region names to close the dialog and focus the first empty or duplicate name in visual order. Select Update the prompt to close it and focus the prompt when a name reference is missing.

After those requirements pass, CAD Scene checks the Edit brief for a hard semantic conflict. It may ask one short question before preparing the mask. This check does not add the Project Composition to Edit. The resolved prompt still has to reference every region name, and the final unmarked-area preservation lock remains mandatory.

A mode conflict opens Review before sending. Select Back to composer to change modes. Select Continue with Edit to send the original prompt under Edit rules. CAD Scene never switches modes automatically.

For an actual clarification question, Skip and Send Now sends the original prompt and stores no clarification. It cannot bypass the source, region, name, or prompt requirements.

Inline name errors appear only after an invalid Send. Changing a region or name clears them until the next invalid Send. See Troubleshooting and recovery for exact recovery steps.

How Edit sends the request

Edit sends the source image, one union mask covering all marked areas, and one compiled spatial prompt in a single image request. It does not send one request per region.

Intersecting named bounds stay as separate spatial instructions. Their shared pixels appear once in the union mask, and every applicable instruction still applies there. Names and bounds are metadata. They are not separate uploaded masks.

If one instruction cannot be prepared safely, CAD Scene uses the marked area's spatial placement and the prompt wording. The render continues with the same source and mask. This recovery does not change the prompt requirements.

What Edit aims to preserve

Edit sends the source with a mask. The render request instructs the model to modify only mask pixels. It also instructs the model to preserve camera, perspective, framing, overall composition, and the existing photographic style.

Generative image models can still introduce small differences or follow a shared boundary loosely. Edit regions are not pixel-perfect layers. Keep regions tight and instructions concrete. Review shared pixels and unmarked edges before accepting a result.

Edit instructs every model to preserve the source composition and aspect ratio. This instruction does not guarantee the original pixel dimensions.

Models with multiple Resolution choices expose supported presets such as 1K, 2K, or 4K. Edit instructs the model to preserve source proportions, so it does not expose Aspect. GPT image models may also expose provider Quality. Exact controls depend on the selected model. The composition-preservation instruction still applies.

Nano Banana models accept up to five Composer references in Edit. GPT Image 2 Edit uses only the source and mask, so its reference control is disabled.

How to review an Edit

Read an Edit comparison in three states. Start with the original source. Next, map each region name to its marked outline. Last, compare the result inside those boundaries.

Check the unmarked edges separately for drift. A sound result follows every named instruction and aims to leave the surrounding image stable.

Static example: Review the source first, then the named outlines, then the result. The instruction asks the model to change marked areas and preserve the surrounding camera, framing, and scene.