OpenMVG v1.6 "Halibut" is out

What's new:

• 24 PR has been handled.
• 22 issues/features enhancement has been completed.

OpenMVG core:

Graphics

• Add a helper class to manage to draw colors from gradient & heat bar/map #1594
• Add opacity support in svgStyle #1697

Multiview

• Add 3 two-view triangulation routines [1,2] Thx to @rjanvier #1623 #1645
• Add Upright Essential matrix solver [3] #1718
• Add relative upright up2p solver [4] Thx to @vlarsson #1721

Matching

• Add HNSWL2 matcher [5] @rjanvier #1665

Software/SfM

• Add ability to chose Triangulation and Resection/Pose method from command line #1729
• Add display of view-graph statistics in ComputeMatches #1662
• ExportToOpenMVS supports now grayscale images @junlinp #1709
• FrustrumExport top face is now colored @csparker247 #1702

Build enhancement

• Fix includes for GCC 9.2 #1666

Wiki

• Initiate a wiki https://github.com/openMVG/openMVG/wiki (with tutorials and description of OpenMVG data structures) #1675

[1] Triangulation: Why Optimize? - BMVC 2019 [2] Closed-Form Optimal Triangulation Based on Angular Errors - ICCV19 [3] Fast and Reliable Minimal Relative Pose Estimation under Planar Motion. Sunglok Choi, Jong-Hwan Kim, 2018 [4] Closed-form solutions to the minimal absolute pose problems with known vertical direction. Zuzana Kukelova, Martin Bujnak, Tomas Pajdla. ACCV 2010 [5] Efficient and robust approximate nearest neighbor search using Hierarchical Navigable Small World graphs Yu. A. Malkov, D. A. Yashunin. 2016