@robert-lieck

- If your frame does not change the marker size, then it inherits the marker size from your fig.data[0].

To get markers of size different from that in `fig.data[0]`

you should define a frame like this:

```
go.Frame(go.Scatter3d(x=x[i], y=y[i], z=z[i], marker_size=2)
```

With a slight modification your animation works.

Namely, I added a dummy trace to keep the scene fixed. Otherwise it moves during the animation and your markers are not visible in the new scene.

I post here two versions: the first one, that displays a single row of markers in each frame, like in your code, and the second one keeps the rows already added:

**1.**

```
import numpy as np
import plotly.graph_objects as go
# generate grid
N = 10
x, y = np.meshgrid(np.linspace(0, 1, N), np.linspace(0, 1, N))
z = np.zeros((N, N))
# plot
fig = go.Figure(
data=[go.Scatter3d(x=[x.min(),x.max()], y=[y.min(), y.max()], z=[z.min(), z.max()], mode="markers",
marker_size=0.05, marker_color="white", showlegend=False),
go.Scatter3d(x=x.flatten(), y=y.flatten(), z=z.flatten())],
# single rows animated via slider
frames=[go.Frame(data=[go.Scatter3d(x=x[i], y=y[i], z=z[i])],
name=i,
traces=[1]) for i in range(N)], #traces=[1] tells plotly.js that each frame updates fig.data[1]
layout_sliders=[dict(steps=[dict(method='animate', args=[[i]], label=f"{i}") for i in range(N)])])
fig.show()
```

**2.**

```
import numpy as np
import plotly.graph_objects as go
# generate grid
N = 10
x, y = np.meshgrid(np.linspace(0, 1, N), np.linspace(0, 1, N))
z = np.zeros((N, N))
# plot
fig = go.Figure(
data=[go.Scatter3d(x=[x.min(),x.max()], y=[y.min(), y.max()], z=[z.min(), z.max()], mode="markers",
marker_size=0.05, marker_color="white", showlegend=False),
go.Scatter3d(x=x.flatten(), y=y.flatten(), z=z.flatten())],
# single rows animated via slider
frames=[go.Frame(data=[go.Scatter3d(x=x[:i, :].flatten(), y=y[:i, :].flatten(), z=z[:i, :].flatten())],
name=i,
traces=[1]) for i in range(N)],
layout_sliders=[dict(steps=[dict(method='animate', args=[[i]], label=f"{i}") for i in range(N)])])
fig.show()
```

LE:

```
fig.write_html("plot.html", auto_play=False)
```

is the fix for the second issue.