Noise points within buildings when simulating radio maps.

[Myzz2003]

Hi!

I'm using the radio map simulation feature in Sionna RT (following the official tutorial but with another 3d scene), but I've noticed that some noise artifacts still appear inside urban buildings. Initially, I thought this might be due to the samples_per_tx parameter being too low. However, even after increasing it to the maximum value of 4,294,967,294, these artifacts remain prevalent. Could you please clarify if there is a known cause for this issue or any effective method to eliminate it?

Any advice would be appreciated!

[jhoydis]

Hi @Myzz2003,

In order for rays to penetrate into buildings, you must (1) enable refraction and (2) ensure that the walls are not too thick.
Can you confirm that what you are observing is not related to this? Can you reproduce the problem in one of the Sionna RT scenes? If yes, a reproducers code snippet would be very welcome.

[Myzz2003]

Thanks for your kind response!

I've been working on this for a while and I found setting the refraction=False in RadioMapSolver won't prevent the noise points from occurrence (please check the buildings in red rectangles):

---

The code that generates this problem is basically the same as the official tutorial on radio maps. I copied the import headers and everything in section Radio map for a realistic scene (and of course added rm_solver definition).

# ----------Omitted-----------
# imports & def config_scene()
# -----------------------------

# Load and configure scene
rm_solver = RadioMapSolver()
num_rows=8
num_cols=2
scene_etoile = config_scene(num_rows, num_cols)

# Compute the SINR map
rm_etoile = rm_solver(scene_etoile,
                      max_depth=8,
                      samples_per_tx=10**8,
                      cell_size=(1, 1),
                      refraction=False,  # Set to false to see the 'penetration' happens
                      )

if no_preview:
    # Render an image
    cam = Camera(position=[0,0,1000],
                     orientation=np.array([0,np.pi/2,-np.pi/2]))
    img = scene_etoile.render(camera=cam,
                        radio_map=rm_etoile,
                        rm_metric="sinr",
                        rm_vmin=-10,
                        rm_vmax=60);
else:
    # Show preview
    scene_etoile.preview(radio_map=rm_etoile,
                         rm_metric="sinr",
                         rm_vmin=-10,
                         rm_vmax=60)

The real problem happened when I tried to access the raw sinr data from a RadioMap instance:

sinr = rm_etoile.sinr
sinr = np.asarray(sinr).sum(axis=0)
sinr = np.nan_to_num(sinr, 0)
sinr = np.log10(sinr + 1e-30) * 10
fig=plt.figure()
plt.imshow(sinr, origin='lower')
plt.axis('off')

And I got the figure shown above.

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