Add QEP 341: add 3D pedestrian view by benoitdm-oslandia · Pull Request #341 · qgis/QGIS-Enhancement-Proposals

benoitdm-oslandia · 2025-06-18T12:58:06Z

Here is an screencast (without the cursor capture) of a POC:

Kooha-2025-06-18-14-46-55.webm

cc @ptitjano

qep-341-3d-pedestrian-view.md

nyalldawson · 2025-06-18T23:24:05Z

@benoitdm-oslandia please announce this to the DEV and USER lists, as per https://github.com/qgis/QGIS-Enhancement-Proposals?tab=readme-ov-file#process-and-policies

benoitdm-oslandia · 2025-06-19T09:49:00Z

@benoitdm-oslandia please announce this to the DEV and USER lists, as per https://github.com/qgis/QGIS-Enhancement-Proposals?tab=readme-ov-file#process-and-policies

I forgot this point! Fixed!

qep-341-3d-pedestrian-view.md

wonder-sk · 2025-06-25T07:38:06Z

Technically speaking, what are the differences between the existing walk/fly mode and the proposed pedestrian mode? (i.e. what would change in QgsCameraController?) From what I understand, the main difference is that the new pedestrian mode would try to keep fixed camera elevation above the terrain, while the existing walk/fly mode allows arbitrary elevation? If that's the case, the existing walk/fly mode should just get an optional constraint "keep elevation X meters above terrain", rather than adding a completely new navigation mode. (here I'm talking only about the camera controller code, not GUI.)

How do you plan to keep the camera at constant elevation above the terrain? Are you going to use QgsTerrainGenerator::heightAt() on every move? (note that for raster DEM terrain the implementation is quite naive and using just a very coarse grid)

benoitdm-oslandia · 2025-06-25T09:14:23Z

Technically speaking, what are the differences between the existing walk/fly mode and the proposed pedestrian mode? (i.e. what would change in QgsCameraController?) From what I understand, the main difference is that the new pedestrian mode would try to keep fixed camera elevation above the terrain, while the existing walk/fly mode allows arbitrary elevation? If that's the case, the existing walk/fly mode should just get an optional constraint "keep elevation X meters above terrain", rather than adding a completely new navigation mode. (here I'm talking only about the camera controller code, not GUI.)

Indeed there is not big difference between the 2 modes but the pedestrian mode needs the user to select the view point to start from.

How do you plan to keep the camera at constant elevation above the terrain? Are you going to use QgsTerrainGenerator::heightAt() on every move? (note that for raster DEM terrain the implementation is quite naive and using just a very coarse grid)

Yes.

benoitdm-oslandia · 2025-07-08T12:10:39Z

@nyalldawson can we call for the vote?

qep-341-3d-pedestrian-view.md

nyalldawson · 2025-07-09T22:24:07Z

qep-341-3d-pedestrian-view.md

+
+A drop-down menu (with the 3 navigation modes) in the "camera" tool in the toolbar to easy the switching from one mode to another.
+
+Once this mode is activated, the user will select where to begin navigation: a marker will be placed vertically above the center of the 3D view. The user moves the marker to the desired location and confirms with a left mouse click or the Enter key.


Can you clarify how the marker is moved? Is this via drag and drop? (And from a technical perspective, how will you handle the marker and interaction with it?)

Can you clarify how the marker is moved? Is this via drag and drop?

The marker follows the mouse moves and is placed on the ground where the mouse cursor is located. There is no need to keep the left mouse button to move the marker and the left mouse click validates the starting point.

how will you handle the marker and interaction with it?

The marker is a vertical rubberband going upward from the ground with a fixed length (2 points, but it could be a triangle). Each time the user move the mouse, the marker position is updated.

qep-341-3d-pedestrian-view.md

nyalldawson · 2025-07-09T22:30:01Z

qep-341-3d-pedestrian-view.md

+The current **Walk** mode will be renamed **Fly** as the pedestrian view is more a real walk mode.
+
+As we will have 3 navigation modes, the 3D UI should display the current mode in use and a way to switch from one to another.
+


There's still technical details missing here. I would like to see in depth details on how you propose to handle the fixed height-above-ground requirement. @wonder-sk pointed out earlier that QgsTerrainGenerator::heightAt() may be inappropriate due to the coarseness of this API -- have you tested to see whether it works and can give a smooth navigation result?

Also: how will you handle walking into the edges of the terrain/nodata areas?

There's still technical details missing here. I would like to see in depth details on how you propose to handle the fixed height-above-ground requirement. @wonder-sk pointed out earlier that QgsTerrainGenerator::heightAt() may be inappropriate due to the coarseness of this API -- have you tested to see whether it works and can give a smooth navigation result?

Indeed. @benoitdm-oslandia has been been working on a prototype to improve QgsTerrainGenerator::heightAt() . It mostly involves two changes:

listen to the DTM texture generation in QgsTerrainGenerator and store them in a cache. The cache has some logic to only keep the highest level when available. This replaces,

in Qgs3DMapScene, when a better level is stored, reload the relevant vector tiles if necessary

Also: how will you handle walking into the edges of the terrain/nodata areas?

Not much can be done in that case, except a fallback to 0 + terrainOffset

Not much can be done in that case, except a fallback to 0 + terrainOffset

Well, you could keep the pedestrian's last elevation so he doesn't fall in potholes/fall off the edge of flat earth 🤣 but rather "float" over them.

Another option would be to interpolate missing values.

Can you add these missing technical details please? Include the proposed changes @benoitdm-oslandia has been testing for heightAt so that voters can make an informed decision.

I made a small fix as the elevation fixes are external to this PR.

Does it look good to you @nyalldawson?

It's ok for me -- but you may want to get those fixes reviewed and merged first, as this proposal depends on them.

Your choice though, we can put this to voting when you're ready.

the elevation fixes are available in this PR

The PR is ready for review here!

nyalldawson · 2025-07-09T22:31:00Z

@benoitdm-oslandia

can we call for the vote?

We can, at any stage you're ready. But in its current form it'd be a -1 from me. I've just added a follow up review with my remaining concerns.

Add QEP 341: add 3D pedestrian view

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nyalldawson reviewed Jun 18, 2025

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nyalldawson added In Discussion QEPs currently in discussion stage Project A proposal which concerns a project, eg new functionality labels Jun 18, 2025

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kannes reviewed Jun 19, 2025

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benoitdm-oslandia added 2 commits June 27, 2025 10:58

remove 2D overlay

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benoitdm-oslandia added 2 commits July 17, 2025 09:49

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		A drop-down menu (with the 3 navigation modes) in the "camera" tool in the toolbar to easy the switching from one mode to another.

		Once this mode is activated, the user will select where to begin navigation: a marker will be placed vertically above the center of the 3D view. The user moves the marker to the desired location and confirms with a left mouse click or the Enter key.

		The current Walk mode will be renamed Fly as the pedestrian view is more a real walk mode.

		As we will have 3 navigation modes, the 3D UI should display the current mode in use and a way to switch from one to another.

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nyalldawson commented Jun 18, 2025

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wonder-sk commented Jun 25, 2025

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nyalldawson Jul 9, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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benoitdm-oslandia Sep 9, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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nyalldawson commented Jul 9, 2025

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