Displacement rendering

Important

It is important to be familiar with the BlenderNC nodetree (PRO mode!) to follow this tutorial, and have completed the previous tutorial: Import ECMWF netCDF and Import ECMWF GRIB.

Some data has been provided by ECMWF, and it is included at the main BlenderNC repository in the path blendernc/test/dataset.

blendernc
└── tests
    └── dataset
        ├── ECMWF_data.grib
        ├── ECMWF_data.nc
        ├── ssh_1995-01.nc
        └── ssh_1995-01.zarr

This example will use the file ECMWF_data.grib, and builds up from the previous tutorial: Import ECMWF GRIB.

Import ECMWF GRIB finished by loading two datasets; mid cloud coverage (mcc) and surface temperature at 2m (t2m).

../_images/change_colormap_rain.png

In this tutorial will explore:

  • creating a displacement of two cloud levels; mid cloud coverage (mcc) and low cloud coverage (lcc),

  • animate three fields of the dataset,

  • and render an animation.

Let’s first add a displacement to the clouds:

  1. In the property menu, switch to the texture property and create a new texture (Rename texture to mid_cloud):

../_images/texture_menu.png

  1. In the texture property menu assign the cloud image as source.

../_images/assing_texture.png

  1. In the property menu, switch to the modifier property.

../_images/modifier_menu.png

  1. In the modifier property, add a subdivision modifier using the simple subdivision and increase the render subdivision.

../_images/modifier_subdivision.png

Important

A larger number of subdivisions will increase the render time. By decreasing the levels of viewports the viewport responsiveness will increase.

  1. Add a displacement modifier and select the texture (mid_cloud).

../_images/modifier_displacement.png

  1. Switch the coordinates from Normal to UV.

../_images/displacement_UV.png

  1. Now let’s reduce the intensity of the displacement modifier strength to 0.05

../_images/displacement_reduce_strenght.png

Note

You can play with any of the parameters; including the displacement texture in the texture property, to smooth and apply a gaussian filter to the image.

../_images/displacement_properties.png

To add another field, for example, the low cloud coverage (lcc), we can duplicate the cloud object (UV sphere) and rename it to Clouds_low.

../_images/cloud_low_object.png

Now we will repeat a similar process, but first we need to create a new image containing the lcc variable in the BlenderNC nodetree:

../_images/new_cloud_low_image.png

Select the Clouds_low object and unlink the material by clicking over the number next to the material name.

../_images/unlink_material.png

Now, we can change the image source in the image texture node in the new material.

../_images/new_image_cloud.png

Similarly to the material, we now need to unlink the displacement texture in the texture property menu by clicking the number next to the name of the texture.

../_images/new_texture.png

Change the displacement image source to the new image Clouds_low.

../_images/cloud_low_texture.png

Now, we can change the colorbar from the default thermal to gray for example:

../_images/new_colorbar.png

Finally, play with the displacement midlevel to achieve a better interpretation of the low cloud coverage (lcc; midlevel = -0.5) and mid cloud coverage (mcc; midlevel = -2). For example, rendering with cycles:

../_images/cycles_render_lcc_mcc.png

Important

If you want to render an animation, you would need to lock the interface of Blender, as it’s a known issue that Blender will crash when animating displacement modifiers.

../_images/lock_render.png