Mesh Modeling in AutoCAD

Hello and Welcome

In this post I will explain you about the Mesh Modeling Technique in AutoCAD. Mesh Modeling is one of the powerful modeling technique in AutoCAD to model freeform organic objects. Dimensional accuracy is not significant in this type of modeling and more importance is rather given to the looks of the object, based on the principle that if it looks right then it is right.

The following is the workflow

a) Create an approximate shape of the object you want to model using Mesh Primitives and 
     custom shapes
b) Manipulate the Sub-objects, so that the model closely resembles what you want
c) Apply an appropriate amount of Smoothness to finish the modeling
d) If necessary convert the Mesh model into a Solid model to take advantage of the
    possibilities of Solid modeling.

Please go through the exercise below to learn Mesh modeling by creating
a double seat sofa.

1.   Choose the workspace as 3d Modeling, View point as SW Isometric and Visual Style as Shaded with Edges. Then click on the Mesh tab.

 

2. Click on the slanting arrow next to Primitives to access the Mesh Primitive Options dialog. Change the Tessellation divisions for the Box to Length = 6, Width = 6 and Height = 3.

 

3. Create a Mesh Box. Click on the Mesh box and click anywhere on the screen to start the Mesh box. For other corners enter the value as @70,60,25. A Mesh box will now be created with Length =70, Width=60 and Height=25 which will corresponds to the sizes for Length, Width and Height respectively.

4. We have to now select the sub-objects for editing. From the Selection Panel click on the Culling to turn it on, if it is not already on. This will make sure that we select only those Sub-objects which are visible in on the screen in the particular viewpoint. Click on the Filter tool and select Face from the drop down. Select the top row of faces as shown in the figure.

 

5. After selecting the faces click on Extrude Faces and give the extrusion value as 10. Repeat the step 4&5 to extrude the face once again to a value of 10, so that the total extrusion is 20 in two steps.

 

6. The space for seating is small now. To increase this we have to stretch the model to both sides. Go to the Front view, select the Vertex as Sub-object from the Selection panel, turn off the Culling(since we have to select all the Vertices in this case) and then select the Vertices on the right hand side as shown and move it along the X-axis of the Gizmo to a distance of 35. Do the same for Left hand side also, so that the model is equally stretched on either sides.

 

7. Select the top row of edges as shown and move it up  a distance of 8. Then select the front edges also as shown and move it forward (along Y-axis) a distance of 3. This will make sure that the model has a round bulgy appearance while smoothing.

 

8. To make the seat, first split the long faces into two by using the Split Face tool. You might need to turn-on Midpoint on edge Object Snap mode on 3D snap to snap it correctly. Split all the faces as shown in the picture.

 

9. To extrude the seating first select the 8 faces toward right and extrude to a value of 1 using Extrude Face. Then select those faces and once again extrude it to a height of 9. Do the same for Left hand side also.

 

10. Once both of the seating is Modeled, select the model and select properties. Look for the Parameter Smoothness under Geometry. Choose an appropriate Smoothness Level so that the model is smooth and curvy. Use the Add Crease tool, if you want to restrict the smoothing to certain faces.

 

11. We have to model the Legs now. For this go to the Top view and select Mesh cylinder from the Primitives and create a Mesh Cylinder of Radius = 2 and Height = 6. Choose Wireframe for the Visual Style. Mirror the Cylinder to form 4 legs.

 

12. The Sofa is now ready. Even though it is not a perfect model you can use many of the techniques explained here to make it better. You can also apply some materials to it to improve the appearance.

 

That is all for now and see you again in another post. I hope this tutorial was useful for you.  If you have any comments, suggestions or questions please let me know. My name is Sunil Mangatt. Thank very much and Good bye.

 

 

 

 

 

 

Exterior Lighting using Sun & Sky along with Geographic location and Shadow study

Hello and welcome. In this post I will explain the procedure to setup Sun & Sky for the purpose of simulating an exterior lighting and to conduct a shadow study. I will also explain setting up a Geographic location for the project.

Exterior Lighting in AutoCAD

First of all let us have some basic understanding about an exterior scene and lighting setup. I have created a very simple scene here with some primitives. This scene can be called an exterior scene, because nothing is enclosed inside any objects. We haven’t yet placed any light in this scene, neither sunlight nor artificial, but still we are able to see the objects. That is because; there are some default lights which are automatically placed on the scene by the program so that we can see things while we create them.

The following is the workflow to setup an Exterior Lighting and to conduct a shadow study in AutoCAD

1. Setup the Lighting Units.

Go to Render Tab click on Lights Panel

The choices are GENERIC, AMERICAN and INTERNATIONAL, depending on what units you use. Use INTERNATIONAL if you are using METRIC system i.e. meters.

 2. Turn off the Default Lighting (so that what is contributing to the illumination of scene is only the lights that we introduce)

Go to Render Tab, clicks on Lights panel and click Default Lighting to turn it on & off.

Also make sure that the Visual style of your view is set to Realistic so that we can see the effects of lighting and shadows in real time in the view port. (i.e. without the need to render the scene)

3. Turn on the Sun

Under Render tab, click on Sun Status to turn on the Sun

3a. Choose a Sky option.

To get the full effects of Exterior Lighting, you must turn on Sky Background & Illumination.

Note: Sky option will only be activated if the View projection is Perspective and will not be available if the View projection is Parallel. You can right click on the View Cube and select Perspective or you can type Perspective in the command prompt and enter a value of "1" to make View projection as Perspective.

 

4. Shadows are next

The two options for SHADOWS are GROUND shadows and FULL shadows. GROUND SHADOW is the shadow which is being cast on the ground. This is a bit tricky. How can AutoCAD determines which is ground. Well for AutoCAD the plane that is passing through Z co-ordinate zero is ground plane. Everything below that is underground and everything above it above ground. This also means that even if you don’t create ground plane, the ground shadow will still be visible if the bottom Z coordinate value of the objects are ZERO.  You can verify the co-ordinate value of any point by using ID command. Just make sure that Z value is zero.

FULL SHADOW is the shadow which is being cast by objects on to other objects.

Click on the arrow next to SUN&LOCATION to access and alter Location of HORIZON , SUN DISK APPEARANCE etc.

5. We have to set the Geographic Location now. This step will ensure that our model is positioned exactly where it is to be located on the Earth, so that the shadow study and lighting analysis are accurate. Setting the location is a bit different in AutoCAD 2014, than up to 2013. In AutoCAD 2014, it is imperative to have an autodesk360 account in-order to view the map. Otherwise we should know the latitude and longitude of the location of our model. However both of them, i.e getting a autodesk360 account or knowing the co-ordinates (just search in google) is easy.

 

After Signing in to your Autodesk account, search & find the location of your project. Click on the "Drop Marker Here" to place a Geographic Marker on the Map. Choose a "GIS coordinate system" which is closer to your local area for improved accuracy.

6. Once the location is set, click on Continue to set the North direction. Move the DATE & TIME slider to see different lighting condition for different times of the day or year and to conduct a shadow study.

That is all for now and see you again in another post. I hope this tutorial was useful for you.  If you have any comments, suggestions or questions please let me know. My name is Sunil Mangatt and thanks for watching. Good bye.