[SVO] Features in images

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I'm having some problems with the SVO package. It says that I need, at least, 100 features. This is a screenshot of how my image can be. What do you recommend? I need the tags to be like that, but I can add other images or something between them.

The terminal says things like:

[ INFO] [1564088158.541837647]: Init: Selected first frame.
[ INFO] [1564088158.631817476]: Init: KLT tracked 99 features
[ INFO] [1564088158.631858874]: Init: KLT 6.79323px average disparity.
[ INFO] [1564088158.667229610]: Init: KLT tracked 99 features
[ INFO] [1564088158.667279683]: Init: KLT 15.6908px average disparity.
[ INFO] [1564088158.736776023]: Init: KLT tracked 91 features
[ INFO] [1564088158.736818202]: Init: KLT 48.4651px average disparity.
[ INFO] [1564088158.753137715]: Init: KLT tracked 84 features
[ INFO] [1564088158.753182410]: Init: KLT 66.3769px average disparity.
[ INFO] [1564088158.753803434]: Init: Homography RANSAC 73 inliers.
[ INFO] [1564088158.753869620]: Init: Selected second frame, triangulated initial map.
[ WARN] [1564088158.816536677]: Not enough matched features.
[ WARN] [1564088158.845805406]: Relocalizing frame
[ WARN] [1564088159.883298395]: Relocalizing frame
[ WARN] [1564088159.884389624]: Not enough matched features.
[ WARN] [1564088160.911127189]: Relocalizing frame
[ WARN] [1564088160.912150758]: Not enough matched features.
[ WARN] [1564088161.983496588]: Relocalizing frame
[ WARN] [1564088162.851545854]: Not enough matched features.
[ WARN] [1564088162.988269923]: Relocalizing frame
[ WARN] [1564088163.865865577]: Not enough matched features.
[ WARN] [1564088164.016926257]: Relocalizing frame
[ WARN] [1564088164.877997931]: Not enough matched features.
[ WARN] [1564088165.037783298]: Relocalizing frame
[ WARN] [1564088166.062333491]: Relocalizing frame
[ WARN] [1564088167.095807976]: Relocalizing frame
[ WARN] [1564088168.096487171]: Relocalizing frame
[ WARN] [1564088169.116208377]: Relocalizing frame

If I add a lot of black and white squares it seems to start working:

but then I move it a little and it fails again:

How can I design the spaces between the tags so the detector recognizes always more than 100 features?