Why does my model look great in RealityCapture, but bad in my 3d program.

Your model is looking great in RC, so you export it and open it up in you 3d Application (in this case Blender) and it does not look so great:

Users often think in this situation that their model did not export properly. The real reason for the difference is in fact the way the object is rendered. The model is the exact same one from RealityCapture. 

The way RealityCapture shows you your textured model in "sweet" mode is "unlit". This way the model doesn't really have a proper material with reflections, specularity, shadows etc..., making it easier for you to see the actual texture, but very hard to see any meshing imperfections in the model. Whereas in the 3d program you can see the effects of lighting and the properties of the material, making all of these imperfections a lot more apparent. It is possible to see a "lit" version of your mesh in "solid" mode:

This is a good way to check the quality of your model before exporting.

It's really bumpy, What can I do about it?

This really depends on what you want to do with your mesh. If your mesh is going to need to have a normal material and be lit, you will need to try and fix the mesh, by smoothing it. If you can get away with having an unlit scene, you can make a shader similar to the "unlit" style you can see in RealityCapture.

Making your object look "unlit" in Blender

This is typically how your shader nodes will look in Blender on import:

You can unplug the color map from the base color, and then change the base color to black, and then plug the color map into the emission input. This effectively turns your object into a glowing light. But this way it will no longer create highlights and shadows, and is effectively "unlit":

Smoothing the mesh

If you want to play around with the material, and also have your model respond to lights and have shadows, it's best to get rid of the bumps by smoothing your model.

Smoothing in RC

The process for getting a smooth result will vary for different models, but for this model first we simplified it down to 40,000 triangles:

And then smoothed it with the following settings:

Now texture you smoothed model, In this circumstance it is better not to use texture reprojection, due to the lumpiness of the original model. You can now export this model to your 3d application and use it in a lit scene. After importing into blender, right click your model and select "shade smooth":

Now that the nasty artifacts are not on your model,  you can make a far more sophisticated shader for your model, and it will look a lot better with lights and shadows in your scene.

Smoothing in Blender

You could also smooth your original model directly in blender. In the sculpting tab in Blender, find the smoothing brush. This example below is the result of very crudely brushing all over the model with the smoothing brush:

If you have the time and the skill you can use all of the sculpting tools to bring back some of the surface detail on your model:

Now your model can be part of a lit scene: