Predicting accurate time of local sunrise in mountainous area? Is there any software which will tell me accurately at what moment any part of the solar disk will become from a specific point on the ground taking account of terrain. I feel like Google maps should have the terrain data I need, and the rest is geometry, but it looks like quite a bit of work, so I wondered if it already existed.

Specifically, I am interested in when a viewer 1.5m above local ground level at latitude 46.497300, longitude 7.714651 will first see direct sunlight on the morning of 1 August 2023, taking account of the surrounding mountains. Ideally I'd like to know how that varies with height above the ground (1-2m) and for locations within 10-20m around that location (in other words, how and when the shadow of the mountains moves off that area).
The PeakFinder app1 can do most of what you're looking for.  It's available for Android and IOS as well as through a web browser.  The app shows the paths across the sky for both the sun and moon2 and displays rise/set times taking into account the local topography and viewpoint elevation3.  At least the Android version works without a network connection (nice for hiking).  IIRC, it uses SRTM data4 for elevations so it's not super-accurate but does a good job over all.

I plugged in the location, elevation (ground + 1m), and date you gave and got sunrise at 05:09 local time, reaching the ridgeline at 08:37 local time.  Here's a link to the page; screenshot is below.

1 I'm not affiliated with PeakFinder, just a satisfied user.

2 If using a web browser, click on the "sun" and "moon" icons on the page's toolbar.

3 It also shows what the surrounding terrain looks like and the names of visible peaks.

4 As does OpenStreetMap, IIRC.


Source: Cropped screenshot of PeakFinder site