fromEquirectangular( equirectangular, renderTarget = null ) {

		return this._fromTexture( equirectangular, renderTarget );

	}
Generates a PMREM from an equirectangular texture, which can be either LDR
or HDR. The ideal input image size is 1k (1024 x 512),
as this matches best with the 256 x 256 cubemap output.

@param {Texture} equirectangular - The equirectangular texture to be converted.
@param {?WebGLRenderTarget} [renderTarget=null] - The render target to use.
@return {WebGLRenderTarget} The resulting PMREM.