CameraRendering.cs

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEditor;
using System.IO;
				
[RequireComponent(typeof(Camera))]
public class CameraRendering : MonoBehaviour {
	public RenderTexture cubemap_left;
	public RenderTexture cubemap_right;
	public RenderTexture equirect;
				
	public float stereoSeparation = 0.064f;		// IPD.
				
	private bool m_firstF = true;
				
	// Use this for initialization
	void Start () {
		Camera camera = this.GetComponent<Camera>();
		camera.stereoSeparation = stereoSeparation; // Eye separation (IPD) of 64mm.
	}
					
	// Update is called once per frame
	void Update () {
		if (cubemap_left == null || cubemap_right == null) return;
				
		// RenderTexture (cube) Rendering.
		Camera camera = this.GetComponent<Camera>();
		camera.RenderToCubemap(cubemap_left, 63, Camera.MonoOrStereoscopicEye.Left); 
		camera.RenderToCubemap(cubemap_right, 63, Camera.MonoOrStereoscopicEye.Right); 
				
		// left and right cubemap to Equirecangular.
		if (equirect == null) return;
		cubemap_left.ConvertToEquirect(equirect, Camera.MonoOrStereoscopicEye.Left);
		cubemap_right.ConvertToEquirect(equirect, Camera.MonoOrStereoscopicEye.Right);		
				
		if (m_firstF) {
			m_firstF = false;
			savePng();		// save png file.
		}
	}
				
	void savePng () {
		if (equirect == null) return;
		Texture2D tex = new Texture2D(equirect.width, equirect.height, TextureFormat.RGB24, false);
		RenderTexture.active = equirect;
		tex.ReadPixels(new Rect(0, 0, equirect.width, equirect.height), 0, 0);
		tex.Apply();

		byte[] bytes = tex.EncodeToPNG();
		Object.Destroy(tex);
				 
		File.WriteAllBytes(Application.dataPath + "/../Unity_SavedScreen.png", bytes);
	}	
}
	

Camera Y	0.25 m

Camera Y	0.5 m

Camera Y	0.75 m

Camera Y	0.95 m

Even changing the height, the size of the room appears bigger than it actually is,
and the sense of grounding of the sphere is weak.

Validation when lowering the camera.

Camera Y	0.5 m
Camera Position Z	-0.2

Camera Y	0.5 m
Camera Position Z	-0.4

Camera Y	0.5 m
Camera Position Z	-0.6