Saving architectural-scale models in location requires an anchor system that can load models in the exact place every time you open the project. Saving a model based on GPS coordinates alone doesn’t work if you are looking for accurate placement, hence why in ARki we have incorporated 2 anchor systems which can be used for mm accuracy: Image anchors and World anchors.
The type of anchor we recommend for 1:1 scale models is based on the site you are augmenting. If you have images/roadsigns available on site, and accurate survey of the site with the position of the images, then Image Anchor can work well! Otherwise we recommend using a World Anchor, and pinning projects to a permanent world feature such as benches, statues, etc.
Checkout the two anchor systems below in more depth, to help you create on-site AR visualisations!
World Anchor lets you save your 3d model in position to any physical object. Once the model is anchored, the app will load the model in position every time the physical object (world anchor) is seen by the camera.
In the demo above we used the physical railway sign as the world anchor, however you can use any static physical object which has enough distinct features. We recommend using objects that are at least 1m in width/height, and have enough geometric variations. For example do not use a flat table, which is reflective, as your physical object.
To anchor the model in place you have to perform a 360 degree scan of the physical object. This allows the app to store as many feature points about the object as possible, so that when you load the project from any perspective it will know how to load it accurately. In the video above we are loading the project by doing a simple scan of the railway sign, which takes a few seconds to load the model in position.
To create accurate world anchors, it is important that the original 3d model is positioned properly on-site. Sometimes moving models at 1:1 scale is not easy if you cannot see the centre of the model, so we recommend using the Add Pivot feature to accurately define a pivot point to your 3d model, and this lets you move/scale/rotate the model more accurately.
In this demo above we are adding a pivot point to the model so that we can move it accurately in position before we perform a 3d scan to save the world anchor..
If your site contains several images such as billboards, large road signs etc, then consider using Image Anchors as an option to save your models in location. To create image anchors that load your project accurately, you will need to conduct a manual survey of the site, to define the exact location of the image in relation to the proposed 3d model.
In this demo above we are pinning a model in place using image anchor, so every time the app sees the defined image it will anchor the model to that image. Image anchors are created inside your 3d software package using a simple textured plane to define as an anchor. We have a series of tutorials which walk through how you can create accurate image anchors inside your 3d software.
For best AR experience, ensure the camera is pointing at the image during the AR session. The larger the image in the real-world the better the tracking experience. For sites that are very large, If you walk too far away from the Image anchor - the app may loose tracking quality, so consider using multiple image anchors so that you can re-localise the model at intervals.
Use images that have distinct features, and shapes, without too many repetitive patterns. This will ensure the most robust AR experience.
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