An introduction to using Wilbur to model terrain in ME-DEM

The basic principles of Wilbur.

Unlike L3DT and Leveller, Wilbur, is the product of development targeted for cartographic and GIS use, not 3D modelling. Georeferencing therefore underpins the whole program. It's best to think of the work space as a map, not a model. This map resides on a globe. Therefore it's true shape is not exactly square, but rather exists in its true state on the surface of a globe. The workspace thus is referred to as a Surface, rather than a terrain,  tile or square.

 World units spacing is determined by the coordinates of the edges of the map- that is the blue square on the screen. The all important Map Info dialog is where this is set up.


Creating a New Terrain.

Open Wilbur.
We have a blank canvas.
Surface > Size.
This sets the size of the terrain surface in pixels.
Set Image Width and Image Height to 1000.
You will see the blue square expand. If the Surface disappears off the bottom of your screen, simply use the Zoom tool to reposition it so that all the surface is visible: Ctrl + -  to zoom out (View > Zoom out 2x). You will see that there are
other zoom controls accessible from the View menu. You will now have something similar to this:




World Scale.

We also have to set the distance that each pixel represents on the map. We do this using the Map Info dialog.
Surface > Map Info.

Lets have a look at the settings and information already present.
We have Resolution, Edges and Miscellaneous Info.
Resolution refers to the distance that each pixel on our surface represents. The Edges run from -1 to 1, both from left to right, and bottom to top. Therefore the map is 2 units wide and 2 units high. I say units, because these are arbitrary, and can be anything that you want them to be. The Horizontal and Vertical Resolution refer to the width and height of your Surface, across and up the screen. Terrain height is given in the Miscellaneous Info. It currently spans from 0 to 1 unit: a blank canvas in Wilbur.
 So how do we get the 0.002 resolution that we have?
If the surface is 2 units wide and we have set the size to 1000, the Surface is therefore split into 1000 pixels along each axis, therefore the resolution = 2/1000 = 0.002.

So you see from this that we have a clear path to setting up our world scale.

The way to set these is by using the Edge settings in combination with the Size of the Surface. The size of the Surface has two measures: the size in pixels that we have just set to 1000, but also the size that this surface is supposed to represent on our phase 2 map: that is, 20Km, or 20000 m.
 We need to tell Wilbur that the edges of the Surface cover 20000 m. Therefore set the left and right edges to -10000 and 10000 respectively. Do likewise with the bottom and top.
 Press OK.

Open up the Map Info dialog again and we now have a resolution of 20 units, or 20 metres for us.


Status bar.

The Status Bar (bottom right) gives the position of the mouse in current pixel location on the Surface. The third figure refers to height. Note: this does not display any of the altitude information present in the Tessellation. It's also possible to have feedback on the cursor of map information via: Edit > Preferences > Show Mouse at Cursor.


Importing the Topo.

I would recommend that you have upsized the topo to a 1K square by this point.

Texture > Shader Setup.
We are now in the Lighting Settings dialog.
Select the Blending tab.
Click the Select Texture Image button.

We are now in the Texture Image Setup dialog.
Browse to the image file and Open.
Before we leave the Texture Image Setup dialog, we need to specify the edges of the texture, just like we did with the Surface edges in the Map Info dialog.
As you guessed, we need the same extents. Set the Left and Right  to -10000 and 10000 respectively. Likewise for Bottom and Top.
Press OK.
Press OK.
This should result in a perfect fit:



The topo tile in this guide was taken from the east side of the Misty Mountains.
 The I.C.E interpretation of the terrain in this area is as follows:
 "This majestic range is also known by the Sindarin name Hithaeglir ("Walls of Mist"). It was thrown up fairly late in their history of the world, possibly at just the time of the Elves' awakening in Cuivienen [see The Silmarilion']. Its effect on the local topography was dramatic: the lands on both sides of the range were lifted and torn by the violence of the event, leading to the creation of broken eroded fells on the western slopes and sheer precipices on the east." [Arnor: Realm, pp 221 ICE #2005]
 The line leading to the foot of the eastern slopes is the Men-i-Naugrim. It was built as a trade route by the dwarves around the Second Age. The road passes through Mirkwood to the east leading eventually to the Iron Hills. At this point I'm not sure what lies at its terminus at the foot of the mountain. It's either a dwarven mine, an entrance to the road travelling under or over the mountains connecting Moria perhaps and ultimately out and onto the dwarven holds in the Ered Luin, or a village perhaps ?....). This landscape lies roughly 60 Km southwest of The Carrock (see 'The Hobbit' ) on the River Anduin.


Saving the Heightfield.

Save the file:
Ctrl+S (File> Save As)  > Save As Type > Binary Terrain Surface (*.bt). Enter a name.
This saves the heightfield including any settings you've made to the Surface parameters.
To open it up: File > Browse to recent files in the list.

Tessellation Tool.

I've closed Wilbur and re-opened the previous file. At this point I have not reinstated the topo.

Wilbur 1.54 has a few recent enhancements. The first we'll look at, is the new Tessellation Tool.
Select the Tessellation Tool on the toolbar along the top (next to the Relight Tool), or Window > Tessellation Tool. 
This will open the Surface Tessellation dialog.
 This tool provides a new method of working within Wilbur. Apart from the Surface Tessellation dialog, the first thing you'll notice is a small '+' sign and a 'T' appear next to the cursor position. It works on a similar principle to a wireframe modeller such as those found in modelling apps such as 3DS Max. It allow us to divide the Surface into a simplified wireframe model: the tesselation. The resolution of that wireframe is set via a combination of the Drag Tolerance field on the right of the
Surface Tessellation dialog and the speed with which you drag the mouse cursor across the Surface. In combination, this sets the rate at which Wilbur samples (records) the position of you mouse cursor, and sets height values: the sampling rate. The higher the sampling rate, the higher resolution your mesh will potentially be.
 The highest sampling resolution is achieved with Drag Variance set to 0 and a slow mouse action. The setting defaults to 10 (pixels).
 Let's try the default setting for now.
To illustrate the wireframe mesh, select:  Surface Tessellation > Display > select all of the three: Show Points, Show Strokes, Show Grid. Deselect Hide All Flat Triangles at Zero.
Draw a circle by Left Click-Dragging on the Surface to get something like this:



Looking at the Surface, one can make out three pieces of information: points, a blue line, and triangles.
The points are called Points, the blue lines are Strokes, and the triangles are the Tessellation Grid. The triangles are the polygons of the mesh formed by connecting up the points. If you mouse over a point, you will activate the altitude readout: the figure in red. Also, you'll see the corresponding point being highlighted in the Surface Tessellation dialog.

Depending on your preferences you can have any combination of this information visible. For instance: look at the Surface Tessellation Dialog. Every point you have just drawn is enumerated here. All of the points have an altitude of zero. You can clear up the display with: Surface Tessellation > Display > Hide Flat Triangles at Zero. This hides all of the triangles which have all three points lying at zero altitude. See below.



Now deselect the Show Points from the same menu item, we have Show Strokes only:

Firstly, the 2D Surface will update. You need to manually update the Heightfield Preview via Update. This is required every time you make a change to the Tessellation or the Surface via any of the Wilbur tools, such as Paintbrush, etc.
 You can see the difference between the two Previews and models below.
To quote the Wilbur developer, Joe Slayton: "The tessellation 3d dialog shows nothing but the current tessellation information. The heightfield 3d dialog shows nothing but the state of the heightfield at the last time it was updated."

The Tessellation Preview is on the left. The Heightfield Preview on the right.

The points along the bottom represent the points in the Stroke. They are all set at 0 altitude. The three important items are: Area High, Area Low and the figure at bottom right.

Now simply move along the profile Left Clicking with the mouse until you have enough points to give a reasonable description of the ridge. I tend to work from right to left. The number of points you insert does not have to match the number of points along the bottom of the window. It doesn't matter: Ignore them for now:

1. Stretch the dialog box so that the highest point on the profile is at the top of the viewing space.
2. Set the Area High field to the maximum altitude that the profile has.
3. Click in the area along the profile to describe the profile with a set of points. Click as many as you like. Don't worry about the points staying along the bottom edge. I find that starting from the right and moving left works best for me.
4.  Make sure that the first and last points (left-right) are not at zero. This means that you might have to set the lowest point which you intended to be zero altitude as non-zero. That's not a major problem.
5. Highlight any point> Right Click > Delete All Points at 0-altitude.

1. Click on the point at the end of the profile.
2. Set its height.
3. Set the Area High to that also.
4. It might be helpful to resize the dialog so that it is in proportion with the Stroke: for instance if you have a very long Stroke that doesn't rise very high, you might prefer to stretch the dialog left-right.
5. Draw your profile by clicking in the space, ignore the points along the bottom (they can be moved up and down, by Highlighting > Left Click-Drag, and Shift Clicked to alter their X Y position).
6. Make sure the end points are not at zero.
7. Right Click any point > Delete All Points at 0-Altitiude.

Erosion.

The following series of images were created as follows:

1. Surface Tessellation > Generate (defaults).
2. Blur.
     This is needed to smooth out the sharp lines on the tessellation. If these persist too much in your model, then the water flow from erosion will only draw attention to them. It's better to smooth them out.
    Filter > Blur > Gaussian Blur > Sigma = 2.
3. Noise.
    The surface needs roughening up.
    Filter > Add Noise > Gaussian (Mean = 0, Variance =20, Use Sea Level = ticked).
    This adds small scale perturbations to the surface. Mean, indicates the average overall value that will be added. Variance =20 specifies variation in height of the noise: 20 m either side of  the mean. Therefore we have a variation between -20m and 20m. In other words it can add or subtract 20m.
4. Filter > Erosion > Incise Flow (Blur= 0, Amount = 1, Flow Exponent =0.266667, Effect Blend = 1).
    This potentially removes significant height from the terrain (see Erosion Table below).
5. Blur.
    This will smooth the Incise Flow  effects.
   Filter > Blur > Gaussian Blur > Sigma= 0.9.
6. Precipiton
   Filter > Erosion > Precipiton Based > (Defaults, except No. of Passes set to between 1-20).
    

Again, the effect may be overplayed, but it makes the ideas and topography clearer.

 You'll notice that there are individual points dotted around. These were used to set point heights using point highlight > Click-Drag  to set the height with the real-time visual feedback of the Tessellation 3D Preview. This is a very quick way to add finishing touches without having to resort to Strokes all the time.

Modelling the Terrain.

 I'm going to really skim over the actual building process here, but we'll look in a moment at a few more specific geomorphologies that I've tried to create.






Erosion..again.

1. Surface Tessellation > Generate (defaults).
2. Blur.
    Filter > Blur > Gaussian Blur > Sigma = 1.9.
    I've used 1.9 rather than the value of 2 that I used previously because the purpose of this Blur step was to smooth out the Tessellation. The Tessellation has already been smoothed out by the additional Strokes on the Surface.
3. Noise.
    The surface needs roughening up.
    Filter > Add Noise > Gaussian (Mean = 0, Variance =20, Use Sea Level = ticked).
4. Filter > Erosion > Incise Flow (Blur= 0, Amount = 1, Flow Exponent= 0.266667, Effect Blend = 1)
    This potentially removes a lot of material from the terrain. For more information see the Erosion table below.
5. Filter > Blur > Gaussian Blur > Sigma= 0.9.
6. Precipiton Based Erosion. Ctrl+E (Filter> Erosion > Precipiton-Based).
    This time I've decided to try to emulate some thermal weathering in the initial stage, and then go on to apply fluvial erosion.
   To quote Joe Slayton: The precipiton algorithm drops a parcel of erosion onto the surface and then moves it downstream until it hits a sink (area with no outflow) or hits its iteration limit.
   
   Thermal Erosion:
   I've used the default settings apart from:
    Max Length = 16.
    This means that the effects of erosion have a length determined by the parameter: its iteration limit of 16. Erosion could stop even when it has not reached a basin.
   Passes = 4.
   Fluvial Erosion:
    Max Length = -1.
   'Max Length is the number of steps that a precipiton is allowed to move before it is done. A value of -1 means that the precipiton will move until it hits a sink so things will take longer over time as the "rivers" get longer.'
    This in effect tells the Precipiton to continue until a basin is reached. Hence, this emulates fluvial erosion.
   Passes = 4.

  Connectivity means whether the system will look at the 4 closest neighbors or the 8 closest neighbors. 4-way is faster than 8-way but tends to generate inferior results.
  Wrap indicates if the precipiton should stop at the edges of the image (None) or treat the world as a cylinder (X only or Y only) or a torus (X and Y). Note that settings wrapping to a value other than None will increase run times but allows height fields that are already connected to remain connected over erosion.

  The Multi-pass group is option relating to multiple passes of the above erosion algorithm.
  Passes is the number of times to run the algorithm.
  Blend is how much the current erosion will be blended with the prior surface. Blending helps to remove some of the worst linear artifacts that tend to appear during the erosion operation due to the connectivity setting.
  Noise is the amount of random noise added to the surface at each iteration. A small value here is sufficient to reduce the amount of artifacts present from the erosion. Note that using too large a value will tend to prevent drainage channels from appearing.'
 

 The Lauterbrunnen in Switzerland has a classic series of hanging valleys. Tolkien stated in his Letters that this was his inspiration for Rivendell: