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.

Flooded fields of the Alamo

June 16, 2017


Colonel Ygnacio de LaBastida, Commander of the Engineers of the Army of the North in 1836, made a map of the area around San Antonio de Bexar and the Alamo compound.  The map prominently featured two ponds just to the east of the walls of the convento courtyard and adjacent to the Alamo acequia (a probable source of the water in the field).  This image depicts a view of the back of the Alamo across one of these ponds.  The vantage point corresponds to a location approximately at the northeastern corner of the present day Alamo grounds.

For this render, I improved the textures on the rear of the Alamo church and convento and continued to experiment with terrain modeling and flora.

Treviño House (Rear)

May 31, 2017


This is a view of the outside of the west wall of the Alamo compound.  The thatched roof structure is the rear of the Treviño house which served as the headquarters of Travis.  In the foreground, there is an acequia that ran parallel to the west wall.  This acequia replaced the one that ran inside the compound.

My recent work has been centered on improving the ground model and workflow.  I reworked the acequias to have a more rustic, ditch-like appearance because I now believe that the dressed stone lining was added later in the 19th century.

To make this scene, the ground was replaced with a relatively small plane with even subdivisions, then shrink-wrapped on the base ground mesh.  The surface was tessellated using a noise texture.  The edge of the acequia was sculpted for a more natural look.  The water shader was improved.  Several types of grass and weeds from the Grass Essentials product were added: a base of short green grass, a pattern of longer brownish grass, longer green grass on the edge of the acequia, a very long yellow/brown grass and finally some nettles.

Some improvements were made to the model of the compound: the poles in the roof  and the bricks in the windows were made more irregular.  Wood lintels were also added.

Photoshop was used to improve the contrast and correct the tone.