Sharpen and linear filtering do actually work correctly on scaled and biased normalmaps because of maths. Doesn't matter if it's tangent or object space. The normal lengths will change slightly with both filters, but I doubt you'd even notice. Since most engines will have linear filtering (straight up or between mip…
You have to normalize the texture after resizing it. If you use nvidia normal map filter, just click the "normalize only" option. You have to do this when you resize a normal map, or paint in one yourself. The RGB value of each pixel has to add up to a specific value. When a normal map resizes down, it may no longer add…
worst that will happen is they'll be a little blured from the down sampling, usually resizing from 2048 to 1024 is better than just rendering with high AA on a 1024, i've had people try and argue with me that it will totally destry the normals if you resize them and they're resampled, but its BS. The most you'll have to do…