fix: add more alts

.github/workflows/jekyll.yml

@@ -75,7 +75,7 @@ jobs:
         uses: chabad360/htmlproofer@master
         with:
           directory: "./_site"
-          arguments: --ignore-status-codes "999,403" --assume-extension .html --swap-urls '^https\://e4e.ucsd.edu/:/'
+          arguments: --ignore-status-codes "999,403"  --enforce_https false --assume-extension .html --swap-urls '^https\://e4e.ucsd.edu/:/'
       - name: Checks files
         run: ls -l cache
       - name: Checks files

_posts/2013-11-27-stingray-testing-at-canyonview-pool.md

@@ -25,10 +25,10 @@ In the video above, color segmentation is performed to extract the green target
 
 **Pictures from Stingray Test**
 
-[![]({{'/assets/2013-11-27-stingray-underwater.jpg' | resize: '150x150'}})]({{'/assets/2013-11-27-stingray-underwater.jpg' | absolute_url}})
-[![]({{'/assets/2013-11-27-IMG_0002.jpg' | resize: '150x150'}})]({{'/assets/2013-11-27-IMG_0002.jpg' | absolute_url}})
-[![]({{'/assets/2013-11-27-IMG_0006.jpg' | resize: '150x150'}})]({{'/assets/2013-11-27-IMG_0006.jpg' | absolute_url}})
+[![stingray-underwater]({{'/assets/2013-11-27-stingray-underwater.jpg' | resize: '150x150'}})]({{'/assets/2013-11-27-stingray-underwater.jpg' | absolute_url}})
+[![IMG_0002]({{'/assets/2013-11-27-IMG_0002.jpg' | resize: '150x150'}})]({{'/assets/2013-11-27-IMG_0002.jpg' | absolute_url}})
+[![IMG_0006]({{'/assets/2013-11-27-IMG_0006.jpg' | resize: '150x150'}})]({{'/assets/2013-11-27-IMG_0006.jpg' | absolute_url}})
 
-[![]({{'/assets/2013-11-27-IMG_0014.jpg' | resize: '150x150'}})]({{'/assets/2013-11-27-IMG_0014.jpg' | absolute_url}})
-[![]({{'/assets/2013-11-27-IMG_3981.jpg' | resize: '150x150'}})]({{'/assets/2013-11-27-IMG_3981.jpg' | absolute_url}})
-[![]({{'/assets/2013-11-27-underwater.png' | resize: '150x150'}})]({{'/assets/2013-11-27-underwater.png' | absolute_url}})
+[![IMG_0014]({{'/assets/2013-11-27-IMG_0014.jpg' | resize: '150x150'}})]({{'/assets/2013-11-27-IMG_0014.jpg' | absolute_url}})
+[![IMG_3981]({{'/assets/2013-11-27-IMG_3981.jpg' | resize: '150x150'}})]({{'/assets/2013-11-27-IMG_3981.jpg' | absolute_url}})
+[![underwater]({{'/assets/2013-11-27-underwater.png' | resize: '150x150'}})]({{'/assets/2013-11-27-underwater.png' | absolute_url}})

_posts/2014-01-09-sony-qx100-quadcopter-testing.md

@@ -53,7 +53,7 @@ We are releasing the interfacing script open source so others can experiment wit
 
 [https://github.com/UCSD-E4E/qx100-interfacing](https://github.com/UCSD-E4E/qx100-interfacing)
 
-[![]({{'/assets/2014-01-09-IMG_1408.jpg' | resize: '1024x682'}})]({{'/assets/2014-01-09-IMG_1408.jpg' | absolute_url}})
+[![IMG_1408]({{'/assets/2014-01-09-IMG_1408.jpg' | resize: '1024x682'}})]({{'/assets/2014-01-09-IMG_1408.jpg' | absolute_url}})
 
 We had much more success with the second approach we tried, mechanically triggering the shutter button with a servo driven from the Ardupilot. Using this method, we were able to quickly and reliably capture images, but without a liveview, framing the picture was difficult. This is relevant for aerial photography, but not for survey missions where the camera should be triggered regularly. Unfortunately, the QX100 has a habit of turning itself off when inactive, which seems to mean not being connected via Wi-Fi, so it cut out the last half of the attempted mapping mission.
 
@@ -62,7 +62,7 @@ The optimal approach we are now aiming for is to have a Wi-Fi liveview with a re
 In terms of achieved image quality, the QX100 is currently not well suited for aerial mapping missions. Due to lack of a shutter priority mode, program auto often chooses slower shutter speeds, which causes significant motion blur from the moving copter. The good news is that it works well while pointed forwards, as shown in the image gallery below. Sony is releasing a new firmware update for the camera at the end of January 2014 that provides a shutter priority mode, so we will try again then.
 
 <figure>
-<a href="{{'/assets/2014-01-09-ebu1-back-night.jpg' | absolute_url}}"><img src="{{'/assets/2014-01-09-ebu1-back-night.jpg' | resize: '640x480'}}"></a>
+<a href="{{'/assets/2014-01-09-ebu1-back-night.jpg' | absolute_url}}"><img src="{{'/assets/2014-01-09-ebu1-back-night.jpg' | resize: '640x480'}}" alt="The back of EBU1 at night"></a>
 <figcaption>The back of EBU1 at night</figcaption>
 </figure>
 
@@ -72,5 +72,5 @@ Hope you enjoy the pictures!
 
 {% for image in page.gallery %}
 <a href="{{ image | absolute_url }}">
-<img src="{{ image | resize: '150x150' }}" width="150px" height="150px">
+<img alt="sony-gallery" src="{{ image | resize: '150x150' }}" width="150px" height="150px">
 </a>{% endfor %}

_posts/2014-01-30-baja-california-site-visit.md

@@ -42,5 +42,5 @@ Below are some photos from our visit to San Felipe. These and more can also be v
 
 {% for image in page.gallery %}
 <a href="{{ image | absolute_url }}">
-<img src="{{ image | resize: '150x150' }}" width="150px" height="150px">
+<img alt="baja-california-gallery" src="{{ image | resize: '150x150' }}" width="150px" height="150px">
 </a>{% endfor %}

_posts/2014-04-05-triton-day.md

@@ -14,12 +14,12 @@ tags:
 Engineers for Exploration participated in the Computer Science & Engineering Project Fair on Triton Day, UCSD's recruitment day for admitted freshmen students. E4E demonstrated the [Intelligent Camera Trap]({{'/intelligent-camera-trap' | absolute_url}}), the [Stingray]({{'/stingray' | absolute_url}}), and 3D models created by the [Aerial Camera Platform]({{'/stabilized-aerial-camera-platform' | absolute_url}}).
 
 <figure>
-<a href="{{'/assets/2014-04-05-riley.jpg' | absolute_url}}"><img src="{{'/assets/2014-04-05-riley.jpg' | resize: '1024x768'}}"></a>
+<a href="{{'/assets/2014-04-05-riley.jpg' | absolute_url}}"><img src="{{'/assets/2014-04-05-riley.jpg' | resize: '1024x768'}}" alt="Riley presenting the Intelligent Camera Trap"></a>
 <figcaption>Riley presenting the Intelligent Camera Trap</figcaption>
 </figure>
 
 
 <figure>
-<a href="{{'/assets/2014-04-05-eric.jpg' | absolute_url}}"><img src="{{'/assets/2014-04-05-eric.jpg' | resize: '1024x768'}}"></a>
+<a href="{{'/assets/2014-04-05-eric.jpg' | absolute_url}}"><img src="{{'/assets/2014-04-05-eric.jpg' | resize: '1024x768'}}" alt="Eric presenting aerial projects and structure from motion models"></a>
 <figcaption>Eric presenting aerial projects and structure from motion models</figcaption>
 </figure>

_posts/2014-04-24-pressure-testing-stereo-rig.md

@@ -18,18 +18,18 @@ tags:
 In preparation for an upcoming expedition to Lake Tahoe, we are building a stereo camera rig. This rig will be carried by a SCUBA diver and used to take stereo images of shipwrecks, which can later be used to create a realistic 3D model of the wreck. Our target wreck is at a depth of 40-50 ft, so we had to verify that our enclosures would remain water tight at that depth.
 
 <figure>
-<a href="{{'/assets/2014-04-24-pressure-test-load.jpg' | absolute_url}}"><img src="{{'/assets/2014-04-24-pressure-test-load.jpg' | resize: '1024x768'}}"></a>
+<a href="{{'/assets/2014-04-24-pressure-test-load.jpg' | absolute_url}}"><img src="{{'/assets/2014-04-24-pressure-test-load.jpg' | resize: '1024x768'}}" alt="Josiah loading our camera enclosures into the pressure tank"></a>
 <figcaption>Josiah loading our camera enclosures into the pressure tank</figcaption>
 </figure>
 
 We were generously assisted by Josiah Renfree of the Southwest Fisheries Science Center, who donated his time and pressure tank to test our enclosures for us. The enclosures remained watertight at a depth of 100ft of seawater, so we are confident that they will work for our Lake Tahoe expedition.
 
 <figure>
-<a href="{{'/assets/2014-04-24-pressure-test.jpg' | absolute_url}}"><img src="{{'/assets/2014-04-24-pressure-test.jpg' | resize: '1024x768'}}"></a>
+<a href="{{'/assets/2014-04-24-pressure-test.jpg' | absolute_url}}"><img src="{{'/assets/2014-04-24-pressure-test.jpg' | resize: '1024x768'}}" alt="The pressure tank in which our enclosures were tested"></a>
 <figcaption>The pressure tank in which our enclosures were tested</figcaption>
 </figure>
 
 <figure>
-<a href="{{'/assets/2014-04-24-enclosures.jpg' | absolute_url}}"><img src="{{'/assets/2014-04-24-enclosures.jpg' | resize: '1024x768'}}"></a>
+<a href="{{'/assets/2014-04-24-enclosures.jpg' | absolute_url}}"><img src="{{'/assets/2014-04-24-enclosures.jpg' | resize: '1024x768'}}" alt="Our newly-tested enclosures"></a>
 <figcaption>Our newly-tested enclosures</figcaption>
 </figure>

_posts/2014-07-21-new-platform-stereo-diving-rig.md

@@ -25,14 +25,14 @@ Introducing E4E's newest platform for underwater remote imaging...the stereo div
 The stereo diving rig is designed to make high-accuracy models of underwater environments by fusing Structure from Motion models from stereo cameras with measurements from a variety of other on-board sensors. The rig contains four on-board cameras - two low-resolution machine vision cameras in stereo, and two DSLR-quality Sony QX100 cameras in stereo - which are used to create photorealistic models of underwater scenes using Structure from Motion algorithms. The rig also contains a compass and pressure sensor, an inertial measurement unit (IMU), and a Doppler Velocity Logger (DVL). These sensors help the rig gain more accurate pose estimates, which can be integrated into our Structure from Motion models to generate more accurate 3D imagery.
 
 <figure>
-<a href="{{'assets/nautical_archaeology/2014-06-17_rig_back.jpg' | absolute_url}}"><img src="{{'assets/nautical_archaeology/2014-06-17_rig_back.jpg' | resize: '1024x768'}}"></a>
+<a href="{{'assets/nautical_archaeology/2014-06-17_rig_back.jpg' | absolute_url}}"><img src="{{'assets/nautical_archaeology/2014-06-17_rig_back.jpg' | resize: '1024x768'}}" alt="The rig on its first deployment at Emerald Bay, Lake Tahoe, CA"></a>
 <figcaption>The rig on its first deployment at Emerald Bay, Lake Tahoe, CA</figcaption>
 </figure>
 
 The rig is operated by a SCUBA diver, who swims to propel the rig around a dive site, such as a shipwreck or underwater cave. The data the rig collects is post-processed after a dive to generate a realistic 3D model of the underwater environment. The rig is designed to go to depths of at least 100 meters.
 
 <figure>
-<a href="{{'assets/nautical_archaeology/2014-06-17_perry-and-antonella-installing-the-camera-housing.jpg' | absolute_url}}"><img src="{{'assets/nautical_archaeology/2014-06-17_perry-and-antonella-installing-the-camera-housing.jpg' | resize: '1024x768'}}"></a>
+<a href="{{'assets/nautical_archaeology/2014-06-17_perry-and-antonella-installing-the-camera-housing.jpg' | absolute_url}}"><img src="{{'assets/nautical_archaeology/2014-06-17_perry-and-antonella-installing-the-camera-housing.jpg' | resize: '1024x768'}}" alt="Assembling the rig for deployment at Lake Tahoe, CA"></a>
 <figcaption>Assembling the rig for deployment at Lake Tahoe, CA</figcaption>
 </figure>
 

_posts/2014-08-14-test-of-aerial-imaging-resolution-for-aerial-surveys-of-vaquita.md

@@ -24,22 +24,22 @@ We plan to fly aerial surveys at an altitude of 150ft. Vaquita can be identified
 
 **Results at 50ft altitude (click for full resolution):**
 
-[![]({{'/assets/2014-08-14-qx-resolution-50ft.jpg' | resize: '200x300'}})]({{'/assets/2014-08-14-qx-resolution-50ft.jpg' | absolute_url}})
-[![]({{'/assets/2014-08-14-qx-resolution-50ft-crop.jpg' | resize: '200x300'}})]({{'/assets/2014-08-14-qx-resolution-50ft-crop.jpg' | absolute_url}})
+[![qx-resolution-50ft]({{'/assets/2014-08-14-qx-resolution-50ft.jpg' | resize: '200x300'}})]({{'/assets/2014-08-14-qx-resolution-50ft.jpg' | absolute_url}})
+[![qx-resolution-50ft-crop]({{'/assets/2014-08-14-qx-resolution-50ft-crop.jpg' | resize: '200x300'}})]({{'/assets/2014-08-14-qx-resolution-50ft-crop.jpg' | absolute_url}})
 
 **Results at 100ft altitude:**
 
-[![]({{'/assets/2014-08-14-qx-resolution-100ft.jpg' | resize: '200x300'}})]({{'/assets/2014-08-14-qx-resolution-100ft.jpg' | absolute_url}})
-[![]({{'/assets/2014-08-14-qx-resolution-100ft-crop.jpg' | resize: '200x300'}})]({{'/assets/2014-08-14-qx-resolution-100ft-crop.jpg' | absolute_url}})
+[![qx-resolution-100ft]({{'/assets/2014-08-14-qx-resolution-100ft.jpg' | resize: '200x300'}})]({{'/assets/2014-08-14-qx-resolution-100ft.jpg' | absolute_url}})
+[![qx-resolution-100ft-crop]({{'/assets/2014-08-14-qx-resolution-100ft-crop.jpg' | resize: '200x300'}})]({{'/assets/2014-08-14-qx-resolution-100ft-crop.jpg' | absolute_url}})
 
 **Results at 150ft altitude:**
 
-[![]({{'/assets/2014-08-14-qx-resolution-150ft.jpg' | resize: '200x300'}})]({{'/assets/2014-08-14-qx-resolution-150ft.jpg' | absolute_url}})
-[![]({{'/assets/2014-08-14-qx-resolution-150ft-crop.jpg' | resize: '200x300'}})]({{'/assets/2014-08-14-qx-resolution-150ft-crop.jpg' | absolute_url}})
+[![qx-resolution-150ft]({{'/assets/2014-08-14-qx-resolution-150ft.jpg' | resize: '200x300'}})]({{'/assets/2014-08-14-qx-resolution-150ft.jpg' | absolute_url}})
+[![qx-resolution-150ft]({{'/assets/2014-08-14-qx-resolution-150ft-crop.jpg' | resize: '200x300'}})]({{'/assets/2014-08-14-qx-resolution-150ft-crop.jpg' | absolute_url}})
 
 **Results at 200ft altitude:**
 
-[![]({{'/assets/2014-08-14-qx-resolution-200ft.jpg' | resize: '200x300'}})]({{'/assets/2014-08-14-qx-resolution-200ft.jpg' | absolute_url}})
-[![]({{'/assets/2014-08-14-qx-resolution-200ft-crop.jpg' | resize: '200x300'}})]({{'/assets/2014-08-14-qx-resolution-200ft-crop.jpg' | absolute_url}})
+[![qx-resolution-200ft]({{'/assets/2014-08-14-qx-resolution-200ft.jpg' | resize: '200x300'}})]({{'/assets/2014-08-14-qx-resolution-200ft.jpg' | absolute_url}})
+[![qx-resolution-200ft-crop]({{'/assets/2014-08-14-qx-resolution-200ft-crop.jpg' | resize: '200x300'}})]({{'/assets/2014-08-14-qx-resolution-200ft-crop.jpg' | absolute_url}})
 
 [1] J. Torre _et al_, "Sexual dimorphism and developmental patterns in the external morphology of the vaquita, _Phocoena sinus_," in _Marine Mammal Sci._, 2014.

_posts/2014-08-31-pressure-testing-openrov-housings.md

@@ -28,7 +28,7 @@ The pressure tubes are made of 1/8-inch thick acrylic, with endcaps made of piec
 The battery tubes were placed in the tank with the epoxy-sealed end downward, and the o-ring seal at the top. The battery tubes leaked early on in the test. The leak was first noticed at a pressure of around 19.9 psi, which corresponds to a depth in seawater of about 45 feet, but probably started at a lower pressure since there were about 1.5 centimeters of water in the bottom of the tube when the leak was first observed.
 
 <figure>
-<a href="{{'/assets/2014-08-31-battery-tubes.jpg' | absolute_url}}"><img src="{{'/assets/2014-08-31-battery-tubes.jpg' | resize: '1024x768'}}"></a>
+<a href="{{'/assets/2014-08-31-battery-tubes.jpg' | absolute_url}}"><img src="{{'/assets/2014-08-31-battery-tubes.jpg' | resize: '1024x768'}}" alt="The battery tubes inside the pressure testing chamber"></a>
 <figcaption>The battery tubes inside the pressure testing chamber</figcaption>
 </figure>
 
@@ -43,7 +43,7 @@ The battery tubes were placed in the tank with the epoxy-sealed end downward, an
 During the test, bubbling was observed from the bottom of the tube where the battery tubes were sealed with epoxy, and the tubes appeared to fill only from the bottom. No bubbling was observed from the top of the tube where the o-ring seal was located. This was likely due to assembly error in epoxy potting the aft endcaps. The epoxy seal appeared to be full of bubbles, which could lead to holes in the seal, and had not completely hardened, suggesting assembly errors in both mixing and applying the epoxy. We will fix the seal on the endcaps and test again to try to determine a more accurate failure mode.
 
 <figure>
-<a href="{{'/assets/2014-08-31-battery-tube-graph.png' | absolute_url}}"><img src="{{'/assets/2014-08-31-battery-tube-graph.png' | resize: '1024x768'}}"></a>
+<a href="{{'/assets/2014-08-31-battery-tube-graph.png' | absolute_url}}"><img src="{{'/assets/2014-08-31-battery-tube-graph.png' | resize: '1024x768'}}" alt="External Pressure on Tube vs. Time"></a>
 <figcaption>External Pressure on Tube vs. Time</figcaption>
 </figure>
 
@@ -53,7 +53,7 @@ The test was run until the tubes were full of water to see if the seal would com
 The main tube leaked as soon as it was put into the tank. We suspect that this was due to manufacturing error in the endcaps, as the lens on our laser cutter may not be properly calibrated and may have cut the endcaps slightly small. Also, the tube may have been slightly warped, since the pieces of the endcaps appeared to be concentric and yet the tube was not evenly sealed along the perimeter of the endcap. Regardless of the cause, the seal was clearly not sufficient to any depth. To counteract this, we lubricated the o-rings with barium grease and wrapped the seals with self-adhesive rubber electrical tape, then wrapped the electrical tape with 20-mil PVC tape. This in situ solution likely contributed to the implosion of the tube, as it prevented any leak from occurring in the o-ring. We will test again with properly-manufactured endcaps to see if the housings fail due to leaking before implosion.
 
 <figure>
-<a href="{{'/assets/2014-08-31-main-tube.jpg' | absolute_url}}"><img src="{{'/assets/2014-08-31-main-tube.jpg' | resize: '1024x768'}}"></a>
+<a href="{{'/assets/2014-08-31-main-tube.jpg' | absolute_url}}"><img src="{{'/assets/2014-08-31-main-tube.jpg' | resize: '1024x768'}}" alt="The OpenROV main pressure tube, with endcaps reinforced with rubber self-adhesive electrical tape and 20-mil PVC tape"></a>
 <figcaption>The OpenROV main pressure tube, with endcaps reinforced with rubber self-adhesive electrical tape and 20-mil PVC tape</figcaption>
 </figure>
 
@@ -69,17 +69,17 @@ The main tube leaked as soon as it was put into the tank. We suspect that this w
 The measured failure pressure corresponds to a failure pressure of 126 psi when correcting for a starting pressure at sealevel (14.7 psi). This is a failure depth of approximately 283 feet in seawater.
 
 <figure>
-<a href="{{'/assets/2014-08-31-main-tube-graph.png' | absolute_url}}"><img src="{{'/assets/2014-08-31-main-tube-graph.png' | resize: '1024x768'}}"></a>
+<a href="{{'/assets/2014-08-31-main-tube-graph.png' | absolute_url}}"><img src="{{'/assets/2014-08-31-main-tube-graph.png' | resize: '1024x768'}}" alt="External Pressure on Tube vs. Time"></a>
 <figcaption>External Pressure on Tube vs. Time</figcaption>
 </figure>
 
 The graph above shows the internal tank pressure (which is the external pressure on the tube) in decibars versus time in minutes. The pressure was increased in increments of 5 psi at first, then in increments of 10 psi later on in the test. The point at which the tube imploded is marked by a red circle. This is followed by a significant measured drop in pressure, which is caused by the volume of the tube being filled by the water, and a subsequent spike in pressure which we speculate was caused by the tank overcompensating for the pressure drop. The pressure then evens out, at which point we turned off the system and let the pressure bleed out.
 
 **Failure Analysis**
 <figure>
-<a href="{{'/assets/2014-08-31-failure-1.jpg' | absolute_url}}"><img src="{{'/assets/2014-08-31-failure-1.jpg' | resize: '200x300'}}"></a>
-<a href="{{'/assets/2014-08-31-failure-2.jpg' | absolute_url}}"><img src="{{'/assets/2014-08-31-failure-2.jpg' | resize: '200x300'}}"></a>
-<a href="{{'/assets/2014-08-31-failure-3.jpg' | absolute_url}}"><img src="{{'/assets/2014-08-31-failure-3.jpg' | resize: '200x300'}}"></a>
+<a href="{{'/assets/2014-08-31-failure-1.jpg' | absolute_url}}"><img src="{{'/assets/2014-08-31-failure-1.jpg' | resize: '200x300'}}" alt="a piece of acrylic with a clean step fracture. This suggests a material defect, since acrylic should produce brittle fractures along material grains."></a>
+<a href="{{'/assets/2014-08-31-failure-2.jpg' | absolute_url}}"><img src="{{'/assets/2014-08-31-failure-2.jpg' | resize: '200x300'}}" alt="Endcap failure"></a>
+<a href="{{'/assets/2014-08-31-failure-3.jpg' | absolute_url}}"><img src="{{'/assets/2014-08-31-failure-3.jpg' | resize: '200x300'}}" alt="Reconstructed endcap"></a>
 <figcaption>Top: a piece of acrylic with a clean step fracture. This suggests a material defect, since acrylic should produce brittle fractures along material grains. Middle: Endcap failure. Bottom: Reconstructed endcap.</figcaption>
 </figure>