Choose texture filtering without material script

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In classic gazebo it was possible to choose the texture filtering in the ogre material script. Since material scripts are not supported in ign-gazebo, I'm wondering how to choose the filter method.

Background: I have a 8x8 pixel apriltag texture. The default texture filtering/interpolation makes the texture look blurry, but i want it to bee sharp. A workaround would be to increase the texture resolution, but I would like to avoid this. The 8x8 px contain all the texture information I need.

Here a picture to illustrate the blurry interpolation