Houdini is a powerful software used for 3D modeling, animation, and visual effects. If you're working on a 3D design project and want to import an OBJ file into Houdini, here's a step-by-step guide to help you do just that.

1. Open Houdini: First, launch Houdini on your computer and open a new or existing project where you want to import the OBJ file.

2. Go to File Menu: Navigate to the File menu at the top of the Houdini interface and select 'Import' from the dropdown menu.

3. Choose OBJ File: A dialog box will appear, prompting you to select the OBJ file you want to import. Browse through your computer's files and select the OBJ file you wish to import into Houdini.

4. Set Import Options: After selecting the OBJ file, Houdini will present you with import options such as scale, orientation, and file type. Adjust these settings according to your project requirements and click 'OK' to proceed.

5. Verify Import: Once the import process is complete, verify that the OBJ file has been successfully imported into your Houdini project. You should be able to see the 3D model within your project workspace.

6. Adjust as Needed: Depending on the complexity of the OBJ file and your project's requirements, you may need to make further adjustments to the imported 3D model within Houdini. Use Houdini's powerful tools and features to edit, texture, and animate the imported OBJ file as needed.

7. Save Your Project: After importing the OBJ file and making any necessary adjustments, don't forget to save your Houdini project to ensure that the imported 3D model is incorporated into your overall design.

By following these simple steps, you can easily import OBJ files into Houdini and incorporate them into your 3D modeling and design projects. Whether you're creating animations, visual effects, or architectural renderings, importing OBJ files into Houdini opens up a world of creative possibilities for your projects.