You’re running into two separate things that sound similar but are not the same:

A texture/image is only “paint” for rendering. It will not make bumps in an STL print. For a normal one-color 3D print, the printer only sees geometry. So applying a Uranus image to a sphere is useful as a visual guide, but it will not create raised or recessed cloud bands on the printed model.

For your school-project goal, I’d do this in ViaCAD as a simple embossed/engraved banded planet, not as a literal bitmap displacement sphere. Uranus is also a good candidate for this because its visible appearance is fairly bland/subtle compared with Jupiter or Saturn.

NASA/Hubble background on Uranus’ subtle visible appearance

Workflow A — reliable ViaCAD-only method: make printable raised/engraved bands

1. Create the sphere

1. Switch the main palette to 3D.
2. Use Solid Primitives → Sphere.
3. The sphere can be made with:
- Sphere 1 Pt
- Sphere 2 Pt
- Sphere Diagonals

For the easiest method:

1. Choose Sphere 1 Pt.
2. Click the center point.
3. Set the diameter/radius in the data entry fields.

Keep the diameter reasonable for printing, for example 60–100 mm.

2. Use the planet image only as a guide

You can apply the image as a render material just to see where the bands are, but don’t expect it to print as shape.

For custom image textures, use BMP or JPEG. Then open Window → Render Library, choose Materials, and drag the material onto the sphere.

Forum users have also run into the same kind of “how do I put an image on a face?” problem. One older PunchCAD forum answer suggested putting the image in the PhotoRender/Textures folder, placing a decal/material, then replacing the image in the Inspector. Another user noted that texture mapping can get tricky when scaling/mapping is wrong.

PunchCAD forum discussion about applying an image/material

Use this as a reference only.

3. Draw the actual printable bands as geometry

For Uranus, don’t try to model every pixel. Make several broad, shallow latitude bands:

1. In a plane in front of the sphere, draw long closed stripe shapes using splines or curves. Think of them as flat “stickers” that will become shallow raised or recessed bands.
2. Make each stripe a closed curve/profile.
3. Use the Cover Surface tool to turn the closed curve boundary into a surface if needed.
4. Use the Wrap tool on the sphere:
- use Emboss for raised bands,
- use Engrave for recessed bands,
- use a small offset, for example 0.3–0.6 mm for an FDM print.

The important tool family is:

Wrap: Imprint / Emboss / Engrave

In “explain like I’m 5” terms: don’t put a picture on the ball and hope the printer feels it. Make shallow cookie-cutter stripes, then wrap those stripes onto the ball.

4. Keep the relief shallow

For a planet, especially Uranus, too much relief will look like mountains. Start shallow:

- raised bands: about 0.3 mm on a small print
- engraved bands: about 0.3–0.5 mm
- very small prints may need more because the slicer/nozzle may ignore tiny details

Make one test band first, slice it, and check whether it shows up.

5. Run the 3D print checks

Before exporting, use the 3D print tools:

1. Run 3D Print Check.
2. Check for:
- too many facets
- size issues
- closed/watertight volume
- duplicated/collapsed facets
- normals
- manifold errors
3. Run Surface Normals Check.
4. Use Preview Slices to inspect whether the part has closed, non-overlapping sections.
5. Export to STL for ordinary single-color printing.

Workflow B — exact image-driven relief

ViaCAD/PowerPack has mesh tools, including HeightMap to Mesh. But that is a heightmap-to-mesh workflow, not a documented “wrap this bitmap around a sphere and turn brightness into radial displacement” workflow.

A PunchCAD forum thread about HeightMap to 3D Mesh is worth noting: one user thought ViaCAD had hung, then reported that it finally converted after waiting longer; they also realized the image had a lot of subtle noise, which created a messy mesh. That matters for planet images because cloud textures are full of gradients/noise.

PunchCAD forum discussion about HeightMap to 3D Mesh

For an exact full-sphere image displacement, the cleaner path is:

1. Use an external mesh tool to create a UV sphere and displace it from a grayscale equirectangular map.
2. Export STL/OBJ.
3. Import it into ViaCAD.
4. Use PowerPack mesh tools and 3D print checks to repair and validate it.

PowerPack mesh repair tools include things like mesh analysis, auto repair, free-edge checks, non-manifold edge checks, collapsed-facet removal, normal fixing/rebuilding, and triangle reduction.

The practical recommendation

For a fifth-grade Uranus model, the best ViaCAD-only route is:

Sphere → draw 6–12 broad wavy bands → Cover Surface → Wrap/Emboss or Wrap/Engrave → 3D Print Check → STL

That will give the print a real, paintable shape without spending hours fighting spherical UV mapping. Texture mapping can be used as a visual guide, but the printed bumps need to be modeled as geometry.