Concepción Dam

August 15, 2017

One of the earliest acequias in San Antonio was known as the Concepción or Pajalache Acequia.  Built in the early 1700s, it served the fields south of San Antonio de Bexar and the Mission Concepción.  The acequia was reputed to be as wide as 20 feet and could be navigated for maintenance by a small boat.  The source of the acequia was a reservoir on the San Antonio river formed by a stone dam near the present-day Briscoe museum and Presa (Dam) Street.

This animation shows what the dam might have looked like in 1836.  My main reference was photos of the Espada Dam south of San Antonio.

This was perhaps my most complex project to date and took about 8 weeks to complete.  Much of the time was spent exploring different workflows to create the waterfall effect.

Blender can simulate water but not at this scale and does not easily produce whitewater (spray, foam and bubbles).  I modeled the dam and basic ground in blender and imported to Houdini which has a complete set of water simulation tools.  After learning how to use the tools an get something satisfactory, I explored ways of importing the simulation back into Blender for rendering.  I was able to get a pretty good result for the basic water but not the whitewater.  I ended up rendering the falls and lower water flow in Houdini and compositing with the rest of the scene from Blender.  The Houdini render at a resolution of 640 x 360 took about 5 hours.

I spent about two weeks in Blender working out the other elements of the scene: deciding on the composition, modeling the dam and acequia gate, and adding the foliage.  The ripples in the reservoir were made by animating a displacement texture in Blender.

I used Photoshop to create a mask for compositing and Houdini to bring all of the elements together.


Testing the model in Unreal Engine

April 6, 2016

Rendering animations in Blender can be time consuming.  Depending on the quality and image size, one frame can take 1 to 3 minutes (or longer!)  Since a second of video is 24 frames, it can take hours or days to render a movie of any interesting length.

So I am studying the use of more realtime solutions that trade some quality for speed.  In particular, I have explored Unity and Unreal game engines.  At the present time, the consensus seems to favor Unreal for graphical quality so that is what I am concentrating on at the moment.

I have spent the last few weeks developing a workflow for translating my model to Unreal (a.k.a. UE4).  So far, I have created a terrain model by making a height map from my Blender mesh and worked out the techniques for porting assets (objects and textures) to work with UE4 materials.  Some additional details that have been worked include the lighting, animating a camera, and rendering an image sequence that can be turned into a video.

The video above is a first test render of the Veramendi buildings on the un-textured terrain.

 


Sun Study of the Connecting Wall

September 11, 2014

I was inspired by a Seth Eastman painting of the north side of the connecting wall between the church of the Alamo and the Convento.  You can see the Watch Tower on the hill in the background.

Painting by Seth Eastman in 1849

Painting by Seth Eastman in 1849

The face of the wall is about was about 10 degrees east of true north and was able to catch only a few minutes of direct sunlight at dawn on a summer day as this painting seems to depict.  A sketch of the same scene is dated November, 1849 but this painting must be from summer as there is no direct sunlight on the wall at that time of year.

This render using the Cycles engine in Blender was done in 240 frames for a simulated June 1849 day.  The Blender Sun/Sky plugin was used for generating the lighting.  The particle system was used for the background trees, grass and stones.  The picket fence was done using a new technique for me that combines the array modifier and the particle system to generate a linear array of element picked at random from a group.  The wall textures were created from photos of the Alamo church and Long Barrack that I took on a trip to San Antonio a few years ago.


The Church of the Alamo Facade

August 9, 2014
Alamo Facade. Clean and displacement only.

Alamo Facade. Clean and displacement only.

My first Alamo model had simple representation of the facade–simple geometry and heavy dependence on low resolution textures taken from photographs.  This model has several improvements.  Using the HABS report, the main features of the facade have been much more carefully modeled.  The helical pattern in the columns is now geometry–not just textures.  The niches, windows and door arch were modeled separately because they have significant displacement from the wall.  Detailed displacement textures were created using Inkscape and applied to features around the doorway, niches and ashlar walls using bump mapping.

This render is a snapshot of the current status of the facade.  To show the detail, the facade is shown without color using only the bump map and displacement textures.  Also, the model is pristine and does not  yet show the effects of damage and weathering.

The statues in the niches are from the original model and consist of a crude geometry displaced by normal maps from a rather low resolution image.  Hopefully, one day, I can improve on them with ZBrush.


Watch Tower and Powder House

July 31, 2014

 

Watch Tower at Dawn

Watch Tower at Dawn (click to enlarge)

 

The Watch Tower and Powder House stood about 2 km southeast of the Alamo on a hill commanding a view of San Antonio de Bexar near the road to Gonzales.  Constructed in the early 1800s by the Mexican Army, it served as an encampment for the cavalry from the third day of the siege.

In this scene, I show the structures at dawn, closely following the sketch of Seth Eastman in 1848.  I suspect the site had more foliage than I have shown but I am using artistic license to show  a bit of the valley below to allow the buildings to receive full lighting from the sun which is very low on the horizon.

Sketch of Watch Tower by Eastment

The Techniques

  • The structures were first placed in my model based on the analysis found in the Alamo Studies Forum.  I used the Eastman sketch as a background image to further align the camera and perspective.
  • The texture for the walls was made by combining a tileable texture created from an image of the Long Barracks and a stucco overlay.
  • The prickly pear cactus stems/pads were modeled by hand and placed in clumps using the particle system.
  • The foreground trees and bushes were modeled using the Sapling plugin which is capable of producing a wide variety of types.  The background trees were Xfrog billboards placed by the particle system
  • The particle system was also used to model the grass–near and far.
  • Finally, the scene is illuminated by an HDR image from Hyperfocal Design.

 


The Alameda

July 8, 2014

The Alameda

The Alameda was an area along the road to the Powder House (now East Commerce Street)  between the Madre and Alamo acequias.  The road was wide and flanked by cottonwood trees that were planted in the early 1800s.  Alameda is a Spanish word for poplar grove.  This was the staging area for the Mexican cavalry on the day of the battle where they waited for the defenders to flee the fort in the face of the main attack from the north.  The place is also significant in that Santa Anna ordered the bodies of the defenders to be burned on two pyres a few yards on opposite sides of the boulevard.

While the exact location of these pyres has been lost in the sands of time, the San Antonio Express (March 26, 1911) published recollections of people who knew the place in an earlier time.  I liked this description:

There was an orchard very near the place where the bodies were burned on the south side of the Alameda, and it is stated that flames and sparks blowing in the fierce March wind that prevailed a part of the time during the incineration blew the flames into the orchard injuring many and destroying some of the fruit trees, most of which died soon after.  This fact probably gave rise to the prevalent belief that obtained for many years, that after the bodies were burned none of the fruit trees in the neighborhood would bear and that they as well as the cottonwood trees all died soon after.  It is a fact that there are now no bearing fruit trees within a block of where either of the two pyres were, and there are but two of the fifty or more cottonwood trees left that grew originally on the Alameda. Neither of them is within a block of either of the pyres.

For many years the Alameda was at the eastern extremity of San Antonio. It extended from where St. Joseph’s Church is now to about a block east of Water Street, or at least the double row of cottonwood trees did. All east of there for some distance and, in fact, as far as the Salado was devoid of trees of any size. The Alameda was about the width of the present Alamo Plaza and about twice as long. It was traversed by three irrigation ditches, each of which furnished moisture for the cottonwood and other trees about it. Flowers also grew there in profusion. It was a beauty spot of the town for many years and was a favorite _____ or pleasure place of the populace, where music either by military or other bands played while the people promenaded. As is the custom today in Mexico, the women and girls walked in one direction, while the men and youths paraded in the opposite, and passing each other instead of promenading together.

Many deadly duels were fought on the Alameda between rival lovers and others who could only appease their anger by shedding the blood of their adversaries. Most of the duels were fought between Mexicans and they almost invariably contended with knives. Some of the duelists used pistols. In the days of dueling the pistols used were those that had single chambers and fired but single charges. They were muzzle-loading weapons and the earliest used had flintlocks.

Reference Images

The Alameda was painted by Texas landscape artist Hermann Lungkwitz in the 1850s.  I used a black and white photograph and a color rendering of his work as my references.

RabaNews_17AlamedaNowEastCommerceSt_1853fromPaintingAlameda

The Scene

My goal was to project the Lungkwitz view of the Alameda back to February 1836.  I attempted to match the aspect ratio of the drawing and artist’s location and field of view.  The post 1836 structures were removed.  The number of cottonwoods were restored  to extend between the acequias and the foliage removed to reflect the time of year.  I decided to match the culvert in detail  including erosion damage even though it probably looked differently in 1836.

The Techniques

This project was a good study in that it required learning many techniques that will be useful in creating detailed renderings of other locations in my model.

  • The land contours  of the foreground were created using Blender sculpting tool.  The background was from my base model.
  • A water material was customized to produce the appropriate reflection, refraction and ripple effect.
  • The foreground “hero” trees and bushes were created using the Sapling add-on in Blender.  I edited the result to give the trees a more natural shape.  Background trees were created with 2D textures from Xfrog applied to planes used as billboards.
  • The background trees were applied using Blender’s particle system.
  • Two types of grass were modeled and applied with particles.  Weight painting was used to control the density and placement.
  • The culvert was modeled in Blender block-by-block to match the pattern in the reference and to increase the realism over a simple applied texture with displacement map.
  • The texture on the stone house was created to closely match the pattern of wear of the plaster as seen in the reference.
  • A slight mist effect was added to the background hills to enhance the sense of distance.
  • The lighting and sky was done using an HDRI sky map from Hyperfocal Design (a very good product).  The sun position was adjusted to approximate the time of day in the reference images.

 


Ballistic render

May 17, 2014

I did some work on the trees in the landscape: the cottonwoods in the Alameda and several peach orchards.

This was interrupted by jury duty and a little work project involving C# and VB. For my birthday, I got a new video card that can be used for fast rendering.  It is based on a new NVIDIA chipset, the GTX 750ti.  Renders of my model are at least 3x faster when using this GPU.  To give it a workout, I animated the trajectory of a howitzer shot from the river battery on the Potrero to the inside of the compound.  Using a standard ballistic trajectory model, I set the elevation at 30 degrees and a muzzle velocity of 62 m/s to drop the projectile into the compound 340 m away.  The time of flight was just over 6.2 s.  At 24 f/s, this came to 149 frames and rendered an about a half hour. Here is the result of the test: