@Override
    public void simpleInitApp() {
 
        
        Geometry model = (Geometry) assetManager.loadModel("Models/Tank/tank.j3o");
        MikktspaceTangentGenerator.generate(model);

        Material pbrMat = assetManager.loadMaterial("Models/Tank/tank.j3m");
        model.setMaterial(pbrMat);
        rootNode.attachChild(model);

        ChaseCamera chaseCam = new ChaseCamera(cam, model, inputManager);
        chaseCam.setDragToRotate(true);
        chaseCam.setMinVerticalRotation(-FastMath.HALF_PI);
        chaseCam.setMaxDistance(1000);
        chaseCam.setSmoothMotion(true);
        chaseCam.setRotationSensitivity(10);
        chaseCam.setZoomSensitivity(5);
        flyCam.setEnabled(false);

        Spatial sky = SkyFactory.createSky(assetManager, "Textures/Sky/Path.hdr", SkyFactory.EnvMapType.EquirectMap);
        rootNode.attachChild(sky);

        // Create baker control
        EnvironmentProbeControl envProbe=new EnvironmentProbeControl(assetManager,256);
        rootNode.addControl(envProbe);
       
        // Tag the sky, only the tagged spatials will be rendered in the env map
        envProbe.tag(sky);


        
    }
A simpler PBR example that uses EnvironmentProbeControl to bake the environment
jme3-examples/src/main/java/jme3test/light/pbr/TestPBRSimple.java