Modeling Roman curtains: Retopology - Part 2

14 Dec, 2014 Usco (3d modeling expert)


What is "retopology" and what does it eat?

A retopology is a change in the topological grid of an object, while preserving its shape as much as possible. Sometimes it is necessary that the grid consist exclusively of quadrangular polygons, or from triangles - for example for games (where you need to use the movement of characters). "Re-topology" is a change in the topology of a three-dimensional object. For example, retopology can be called a decrease in grid density, well, or in general, any change in edge loop flow. The shape of the object does not change much, but the grid of the edges changes so as to approximate the object more accurately. A special case is to change the topology of an object so that only square faces remain.

Importing a model in 3ds Max

I will open 3d max.

I select the Import category in the Menu and the import item of the same name in it. Import:

Then select the file with the optimized model in obj format and click Open. The window for import options selection will appear, I will tick the box as shown in the picture, press Import:

After importing, the curtain will be highlighted automatically:

For retopology, we need a second curtain in the unfolded form. Before importing the second version of the curtains, you need to rename all the elements of the first one so that there is no match of the names. Select all, and in the main Tools menu, select Rename Objects:

After these actions, all elements of the first curtain will be named as follows:

Next, slightly shift the main curtain, this is to ensure that when importing the second option, there is no overlapping on each other, because it will take its place:

I configure the display of statistics - the number of polygons. In the perspective window, click on the plus [+] and select ConfigureViewports ...:

Next, I'll go to the Statistics tab, and I'll select the items in it as shown in the picture:

I import the second (expanded) version:

Note: The colors for the import may vary.

Then rename the new items. For an example I'll call them Template. Here is what will happen at the moment:

Retopology in 3ds Max

I will examine the seams on the central element. For the formation of one of the sweet, it took about 4 ribs, for another 3:

I'll build a simplified version based on it. For this I hide all the other elements:

Select the 3D binding (Snaps Toggle) and configure it:

I'll wrap a simple spline around the entire element, "tied" to the extreme-corner points:

Convert to Editable Poly, I cut it in half:

I'll add edges by following the pattern:

Note: In the future I will use the tools on the Ribbon panel:

These edges are added very easily if you use the Swift Loop:

But, if there are no problems with the lower and lateral edges, then as soon as I want to build a strictly horizontal edge a little higher, Swift Loop will continue to build it "angular", tilting along the lower edges, rather than over the top horizontal:

To fix this, I'll do the following.

1. Put the edge anywhere (it will be highlighted in red). Next, a marker appears in the form of a supposed edge for the next construction. It will move along with my mouse pointer (circled in a green circle) - I do not pay attention to it yet:

2. Press Ctrl + Alt (the marker will disappear for a while, only the previously constructed edge will remain). DO NOT RELEASE Ctrl + Alt I'll build a new edge - moving the mouse with the old one. At the place where the old rib stood there was a white square. I can move this square (by setting the edge to this place, and releasing the mouse button.) Mouse key is released only - Ctrl + Alt is CLOSED). Next, move the mouse to the desired location with the mouse. The point is that there will be a "corner" edge up to the square, and then a "horizontal" edge. I will set the edge using the template. The rest of the edges I'll build without the keyboard shortcut Ctrl + Alt. After building the main edges, the Swift Loop mode is turned off:

I will add additional edges for the seams using RingMode and Connect Edges, according to the plan:

I'll open all the previously hidden items:

Now I have:
A - main curtain
B - template
B - optimized (I pushed it away from the template - so it was visible for an example)

Next, I'll put pattern B in the form of the original A. The Morpher modifier answers for this:

After that, I'll make sure that the optimized Blur also repeats the outlines of the template B. To do this, you need the Skin Wrap modifier. After applying, I look at the percent counter, it should reach 100% and "disappear":

You ask: - And why not immediately apply Morpher to the optimized B?

The fact is that Morpher reacts to the number of coincident points. If the points are not the same number, then it will not work, but that's not all, it will move the points to the place where the "original" points of the parent object are. In other words - if there is a square and a triangle, and both have the same number of points, then applying Morpher to a triangle, it will tend to turn the triangle into a square, "stretching" the points.


Now it is necessary to make the correct layout on the central element of the curtain. To do this, create VrayMtl in the diffuse slot put the Checker card:

On the optimized curtain B I will assign the created material, as well as the UVWMap modifier, Planar type, the size of the height and width are the same:

Next, I will "fold" the blind. To do this, you need to adjust the value from 0 to 100 in Morpher:

Here's what happened:

Now I will make optimized sidewalls. To do this, take a simple Plane and build on the contour of the original with a snap, adjust the value of the number of edges vertically. The rest of the edges I add using Connect Edges, focusing on the central part:

I'll make a copy, and move it with the binding to the other side:

I will deal with the lower elements. First, I'll build a spline from the Line, convert it to Editable Poly:

Ribs I will add only to those places where there is a strong "crushing" of the fabric of the original:

Ribs I will add only to those places where there is a strong "crumpling" of the fabric of the original.

After I make the 1st element, the rest I will make its copies and reflect them horizontally and vertically. I will move with a binding. Next I'll assign each modifier Morpher and Skin Wrap as I did with the center element:

I will tweak all the necessary values ​​in Morpher to 100.

Do not forget to apply the UVWMap modifier, the Planar type for all parts of the curtain:

Compare with the original:

Number of polygons before and after "retopology":

All the "optimized" elements with the Skin Wrap modifier are converted to Editable Poly, the rest I delete. The curtain is aligned to the center of coordinates. I'm safe.

The blind is ready.

Note: MarvelousDesigner 4 (this version) has the additional ability to build a square grid. To do this, select all the component curtains, go to the PropertyEditor and select the grid type Quad from the Misc submenu:

But if you look closely at the created grid, you can see that it is built a little crooked and contains a small number of triangles, although it reduces the number of polygons of the grid in comparison with the original - completely triangular:


Retopology curtains in Zbrush

Let's consider one more variant of blind retouching in the program ZBrush4R6. We will use this version of the program. Only it has a wonderful tool ZRemesher.

Open ZBrush. When you open the program it will look like this:

Remove the popup menu Light Box:

The next step is importing curtains into ZBrush.

Click on the Import button, select our curtain in obj format, click on Open:

In this case, we will see how the model appeared in the list of imported objects:

We will rise in the main window of the program and we will pull the mouse, having clamped the left button - the curtain will appear in the program:

Click on the Edit button to edit the model:

To display the model grid, click the Poly F tool:

If we take the rotate turning tool and turn the curtain on the wrong side, then we see that from the underside, where there is no so-called double geometry (one-sided plane in fact), the curtain plane disappears from visibility:

To display the geometry worked in any case, click the display button Display Properties - Double:

For retopology, go to the menu Geometry - ZRemesher:

In ZRemesher, click the following buttons - Freeze Border (freezing the boundaries of the object, it is necessary to ensure that when retopology blinds do not lose their basic forms). Then click the ZRemesher button:

ZBrush will start the miscalculation of retopology, which will be discussed by the miscalculation line in the top line of the program:

Wait until the rendering is finished, after which you will see how the grid of curtains has changed:

If for your purposes the grid turned out to be shallow, then you can change the Target Poligon Count parameter when retopology, the smaller it is, the larger the grid. And also you can use the Half buttons (half of the source), Same (also the number), etc .:

In this case, I used the Target Poligon Count value of 30.

ZBrush is not a good person, does not save the sweep on the model when importing obj format. (When exporting from Marvelous Designer, our curtains had a sweep).

Therefore, we will have to do it.

Let's go to Zplugin - UV Master:

Turn Symmetry symmetry off and enable Unwrap:

Click Check Seams (check the seams), as well as the Flatten button (see the sweep):

To exit the scan window, click UnFlatten:

Next, you need to export the curtain to obj:

We import the curtain into Max, count the number of polygons:

Let's see how ZBrush unfolded the blind.

For this, I use a card similar to a Checker card, but with a direction:

Put it in the diffuse slot of the standard VRayMtl and assign the material to the blind:

I see that ZBrush (a bad person this is no longer to be called!) Made a sweep at an angle. To fix it, I'll select all the elements of the curtain, assign the Unwrap UVW modifier to them, open the sweep window and rotate the curtain elements as I need:

I'll check how the scan lies on the model

Same again! The figures look in the wrong direction:

I'll go into Unwrap UVW and mirror all the elements horizontally:

Well, finally it turned out!

Note: The operation to unite the parts of the curtains into a single Poly object is required in any case, regardless of how the model was retopulated.

I apply to the main fabric one material:

And to all bokovinkam another:

Select all the elements, convert them to Editable Poly:

I go into the Editable Poly of any element, click on the Attach button and click all the remaining elements:

When you join the items, such a window pops up. Put the parameters like in the screenshot below:

After combining all the elements into a single poly we take the material of the curtains with a pipette and see that it has become a Multi / Sub-Object:

In this lesson, we examined several variants of the model's retopology, using the example of curtains. Each of them can be used by you depending on the specific situation and the task before you.

As they say - Choose your own option!

27 Dec, 2014 Andrey
27 Dec, 2014 # Re: Modeling Roman curtains: Retopology - Part 2
Thank you for the lesson, use of Brasov usual! The first lesson on this subject too much help!

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